GTA
All Springer/NP/PCP Air Gun Discussion General => European/Asian Air Gun Gates => German AirGun Gate => Topic started by: jimk1963 on June 20, 2022, 10:40:27 PM
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Hi All, have an Anschutz 380 that was rebuilt by Randy Bimrose about 10 years ago, using Maccari-supplied piston/breach seals. After re-build, gun did (and still) shoots only about 560fps with 7grain wadcutter, and about 485fps w/ 8.1 grain wadcutter. Seems on the low side, should be closer to an FWB 300 at 650fps. Blue Book of Airguns says "600-640fps", can't find the 380 in any of my Beeman or ARH catalogs from the 80's. It's also burping out tiny bits of oil into the breech with every shot - I thought this type of gun would/should have very little oil in the chamber, nearly zero in fact. So not sure if that means something is wrong, like a piston ring gone bad or other issue. Questions:
1) Anyone know what velocity I should be looking for? Say, with 8.1 grain wadcutter
2) I'm considering disassembly. Found the parts diagram and owners manuals on Anschutz archives, but this thing has nearly 150 parts and the exploded diagram is frankly not very helpful to the unfamiliar. Anyone know of any videos or written info to aid in tear-down?
Love this gun, it's a joy to shoot. Would like to see if there are some simple things I can do internally to restore power and get rid of its oil burp.
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Hmm, lots of looks but no inputs... something I said? ;) The 380 didn't sell like the FWB's, seems to be very little info or interest in this model. Shame, it's a joy to shoot and looks fantastic. Believe Randy is still servicing guns, will have to check in with him on possible next steps.
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I have never had one apart but would assume like you they go together on the dry side. I have rebuilt a few FWB300 and they get minimal lube.
How and where do you store it? Is it possible whatever lubes he used have separated? If it isn’t dieseling it probably is not petroleum based lube.
This is a more Olympic style shooting forum. You might get and answer here.
http://www.targettalk.org (http://www.targettalk.org)
And the 380 was arguably the best ten meter spring gun ever built. 🤗
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Hi All, have an Anschutz 380 that was rebuilt by Randy Bimrose about 10 years ago, using Maccari-supplied piston/breach seals. After re-build, gun did (and still) shoots only about 560fps with 7grain wadcutter, and about 485fps w/ 8.1 grain wadcutter. Seems on the low side, should be closer to an FWB 300 at 650fps. Blue Book of Airguns says "600-640fps", can't find the 380 in any of my Beeman or ARH catalogs from the 80's. It's also burping out tiny bits of oil into the breech with every shot - I thought this type of gun would/should have very little oil in the chamber, nearly zero in fact. So not sure if that means something is wrong, like a piston ring gone bad or other issue. Questions:
1) Anyone know what velocity I should be looking for? Say, with 8.1 grain wadcutter
2) I'm considering disassembly. Found the parts diagram and owners manuals on Anschutz archives, but this thing has nearly 150 parts and the exploded diagram is frankly not very helpful to the unfamiliar. Anyone know of any videos or written info to aid in tear-down?
Love this gun, it's a joy to shoot. Would like to see if there are some simple things I can do internally to restore power and get rid of its oil burp.
The 380, as all other Match style guns, was rated to 5.5 ft-lbs. Most were at about 5.3 ft-lbs OEM just to make sure that if you won, you would not be disallowed on the grounds of excessive power.
It is a rarity nowadays given that so few were made.
There are tens of thousands 300's floating around because it was the preferred "club" gun in Germany. But very few 380's
It is a complicated gun but MOST parts are in the trigger control section, the power section being fairly simple (as Olympic Match guns go).
IIRC, once you take apart the stock the power section/barrel comes out of the sheath as a unit.
IF the gun is spitting lube, then someone oiled the gun somewhere and slowly the oil migrated into the compression chamber.
Lewis Rheingold (lewisbelinda@yahoo.com) and Neal Johnson (neal@nealjguns.com) used to be the "Go to" guys for spare parts and service for these guns.
Perhaps these pictures (not mine) can help some, first a "sectioned" gun:
(https://imagizer.imageshack.com/v2/1024x768q90/922/3yPDN2.jpg)
(https://imagizer.imageshack.com/v2/1024x768q90/923/MeRXYy.jpg)
(https://imagizer.imageshack.com/v2/1024x768q90/924/Wow08T.jpg)
(https://imagizer.imageshack.com/v2/1024x768q90/922/KbrwYj.jpg)
As well as these from a disassembly:
(https://imagizer.imageshack.com/v2/1024x768q90/923/US5NWN.jpg)
(https://imagizer.imageshack.com/v2/1024x768q90/923/jp6yAi.jpg)
It is worth noting that the piston uses a bronze ring seal and a buffer, and that the springs' (2 springs) guide (1) is, in reality part of the piston.
In MOST cases, it is the internal, small diameter spring the one that breaks.
Good luck, keep us posted!
HM
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Thanks so much Hector, fantastic information. I’m getting 4.2-4.9 ft-lbs at present, seems to confirm it’s on the low side.
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Grew tired of constantly fighting the Chrony Beta, whether it be the lighting, or the fussy canopies, or the "for no obvious reason" misses it seems to have. Broke down and bought the Air Chrony MK3 from AoA - love it, love it, love it. Not a single miss, much easier to set up (no set up really), has AC power and battery option... just a much better chrony all-around. Measured two 10-shot groups with the following results:
Diabolo Basic 7.0 grain
10 shot group
5.00 fpe avg
567 fps avg
555-577 fps
Std Dev 6.7fps
RWS Meisterkugeln 8.2 grain
10 shot group
4.7 fpe avg
508 fps avg
493-527 fps
Std Dev 12.1 fps
Based on Hector's info, appears the gun is firing 0.5+ ft-lb lower than it should. Velocity spread also seems pretty large for a 10m match rifle. Believe my FWB 300's shoot with a spread of <10fps over a 10 shot group.
Shooting some 10m targets, I'm finding that with each 5-shot group. there usually seems to be one "flyer". I'm guessing the wide spread in velocity is contributing to this. It's worse with the 8.2g Meisterkugeln pellets, a little better with the 7g Diabolo Basics.
The gun has also stopped spitting oil into the breech, which is hopefully a good sign.
I can see the new red-colored piston seal that Randy installed, along with the new red breech seal. Not sure if he was able to change out the brass piston ring, nor am I sure how critical that ring is to ensure velocity. Seems atypical for the piston to have a ring like this. Then again, also atypical to have two springs...
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Actually, Jim, it is not that atypical. EARLY FWB 300's also used bronze Rings. And those things are eternal.
You CAN do that when the compression chamber is honed to near perfection.
The two spring thing is not that rare and nowadays there is an Eastern European company that makes sets for many more guns.
Have you ascertained if the two springs are there and healthy?
My guess is that the wide variation in MV is due to a broken inner spring.
JM offers the spring set: https://www.airrifleheadquarters.com/catalog/item/251488/10190174.htm (https://www.airrifleheadquarters.com/catalog/item/251488/10190174.htm)
I would make the effort to see if the springs are OK.
The OTHER possibility is that the buffer degraded with the oil and there are bits of mush everywhere creating a problem. A good cleaning and the replacement of the buffer would solve the problem.
While these guns are not THE best ever Match Spring piston guns ever built they are easily in the top two.
;-)
They do deserve to shoot to their potential.
HTH, keep us posted!
HM
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Thanks again Hector, missed "page 2" on JM's website, where the 380 was lurking. Good to know springs are still available.
Haven't explored the internals yet, still not sure how to disassemble. Assume the major steps are (1) separate shroud from barrel/receiver, (2) remove trigger assy intact, (3) release spring tension and slide out the guts.
Step 1 isn't obvious to me... have been staring at this receiver for a good while, and am probably just missing something obvious.
Snapped some photos of this SN 9077 unit, in case anyone has info/advice.
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Pics:
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Go to this website:
https://ia800400.us.archive.org/18/items/gunmanual_Anschutz_380/Anschutz%20380.pdf
Download the document.
Page 34 are the disassembly instructions in "English"
If you can, donate to Internet Archive, it is a non-profit that holds a LOT of info free for all to use.
HTH
HM
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Thanks so much Hector! That was precisely what I needed. I was able to disassemble the gun without issue. Guess what I found? A pellet was smooshed up against the front wall of the compression cylinder!
Some pics below to illustrate. If you look at the pic with piston seal and flat pellet, you can see the imprint the pellet left on the face of the piston seal. Hard to see but it's there. I had previously purchased extra piston seals from Lewis Reinhold so I just popped a new one on. The brass piston ring looks pristine, don't see any issues there.
Not sure how it's possible for a pellet to get into the compression cylinder - I guess Randy may have missed it, because the gun was shooting low immediately after the rebuild. Or is there any way a pellet can "fall into" the compression chamber? I can't see how, unless a pellet smaller than the breech seal opening somehow got in there, but not sure how could this happen...?
Mainsprings are both intact, not broken, I assume they are fine as-is. I will go ahead and order new springs anyway though since I am able to take the gun apart. The springs are lubricated with some kind of grease, seems a bit messy to me so will clean that up.
Last remaining question is lubrication. The piston rides inside the compression cylinder. Am thinking to put a tiny bit of moly on the fore and aft ends of the piston, and maybe a tiny bit on the cocking lever. That's it. Sound about right?
I can't believe how much fun I just had taking this beauty apart!
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Ugh, disappointing result. Cleaned the parts using an ultrasonic cleaner (Simple Green diluted with distilled water - compression chamber, piston, 2 springs), replaced the piston seal, applied moly very sparingly to piston, gun went back together easily. But power is even lower than before, much lower - 3fpe. I did not re-apply grease to the springs, and did not apply any lube in the compression chamber. Wondering if this is a friction issue or something else.
10 Shot Group
RWS Meisterkugeln 8.2g
Eavg = 3 fpe
Vavg = 406 fps
Vmin = 381 fps
Vmax = 426 fps
Spread = 45 fps
StDev = 15 fps
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You're too fast for me. LOL!
Yes a smallish pellet CAN fall BACK into the compression chamber, this is a feature of the design of guns that try to do away with TP's by using a conical breech and recessed compression chamber face.
If you look at this picture of the sectioned gun I posted it is clear:
(https://imagizer.imageshack.com/v2/1024x768q90/922/KbrwYj.jpg)
The red thing you replaced is not a seal, it is buffer and I assume you also replaced the seal between the compression chamber and the barrel. So, questions and comments:
1.- Are the springs straight? (roll them across a glass surface). If they are a bit crooked/wavy, it is not a problem, but they will require more lube to work as expected.
2.- Moly is a BAD idea. Clean everything again and lube with Ultimox 226. You can apply enough (but not too much) to all surfaces, it will not diesel and, Ultimox, as opposed to Krytox, will not absorb humidity.
3.- Are seals good? with the gun UNCOCKED, blow into the barrel (not the sheath). If you can feel air escape, you will need to replace the seals.
4.- Would be pretty strange, but is the bronze ring good? Do the same blowing test with a de-sprung gun in the COCKED BUT NOT LOADED position. Bronze ring DOES require some lube to work properly. Ultimox again is your friend, if you are impatient and do not want the whole thing to settle in again, Ultimox makes an oil that can be used in the bronze ring without contaminating the whole lube job.
And this is important: Changing buffers and breech seals in Match airguns is like getting a new gun. You will need to allow at least 2-300 shots to settle back in.
Match rifles are the "Diva's" of the air rifle world, they will make your hair go gray, they WILL drive you up the walls, they will make you cry in despair; but when they perform, you forgive them everything.
;-)
Keep us posted!
HM
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Thanks Hector!
1) Thanks for the pellet-in-chamber explanation. Yes, I can see how easy it would be for a loose pellet to fall back into the chamber, looking at your cutaway. Yikes. I guess the only solution for that is to pick the "right" pellet with enough interference fit to sit snugly.
2) Sorry, yes piston buffer, not piston seal. It's certainly not sealing anything, doesn't even reach the walls of the chamber. Appears to just buffer the piston from slamming into the end of the chamber I suppose.
3) Springs did not lay straight, both had a slight bend in them. Also, I forgot to snap a photo, but I'm sure the inner spring is actually an inch or two shorter than the outer spring. On the WFC site, and Maccari's site, the springs appear to be the same length. I wonder if the inner spring had broken in earlier years and the owner didn't replace it, but rather just kept using the shorter spring. I will inspect again. Have already ordered springs from JM, they'll be here Friday.
4) I will lube up the springs as you mentioned. I watched a number of rebuild videos, and found that several guys don't like to put any lube on the springs of these match rifles. So I went with minimalist approach first to see how she did. You recommend to lube the springs with Ultimox?
5) I'm confused about Ultimox vs. Moly. 40 years ago, moly paste was the go-to lube for these guns. JM still sells moly paste, and does not sell any PTFE lube (not that I saw anyway). Moly should work, and even if there's minor dieseling for a few shots I'm not overly concerned with that. I'm in USA, not EU where velocity can be a worry. That said, have ordered some Ultimox 226 off Amazon, but takes a week to get here... :-(
6) Seals - I only replaced the piston buffer, not the breech seal which still looks brand new. I will try the blow tests to see if there are leaks. I'm not quite sure how to remove the breech seal, it sits behind a black plastic ring at the head of the compression chamber. Not sure if that black ring has to come off first, and if so, how to remove it without damage. It's on there really tight.
7) Bronze ring - not sure how to tell if one of these is "good" with certainty, but after a good degreasing the ring was super smooth, shiny with no nicks/marks/potholes of any kind all the way around it. Basically looked good as new from what I could tell. That said, I do wonder if these rings fatigue over the years? Maybe it's not pressing against the compression chamber with as much force as it did when new. The amount of deformation is tiny so I wouldn't expect the ring to ever take a set, but 40 years is a long time.
8. 200-300 shots... understood that it should take a bit of shooting for the gun to settle down. However, I wouldn't expect the gun to shoot 150fps slower after a tune, that number must indicate a significant problem - right? I mean, I've read and watched other tune-ups and the initial velocities are only a small percentage lower than final, maybe 5-10% max. In this case I'm 30% down in velocity, and essentially all I did was replace the piston buffer and add a truly tiny amount of moly. Maybe too tiny.
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James,
One of the real advantages of Ultimox vs Moly paste is that it is not temperature sensitive. In cold weather or hot and humid, it should shoot to the same POI. This is not true with Moly. Yes, the fact that it does not combust is nice but the true advantage lack of temperature sensitivity. ;)
-Y
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Thanks Yogi, I'm in San Diego County, weather doesn't vary a lot down here and humidity is pretty stable too. But appreciate that science has come along since my 40-year old education. :-D
So I did two things today:
1) Rebuild gun with moly and run chrony (added Moly to piston ring, piston body, compression chamber - ultra thin application, Moly not even visible on surfaces; also added JM's "light tar" to both springs, also very sparingly)
2) Degrease springs/piston/compression chamber completely (using ultrasonic bath), apply Krytox GPL 205 in same places, and run chrony (Ultimox is on the way but won't be here for another week; was able to get Krytox same-day on Amazon)
Results:
1) Moly
10 shot group, RWS Meisterkugeln 8.2g
Eavg = 3.1 fpe
Vavg = 410 fps
Vmin = 392 fps
Vmax = 436 fps
Spread = 44 fps
StDev = 13 fps
2) Krytox
10 shot group, RWS Meisterkugeln 8.2g
Eavg = 3.41 fpe
Vavg = 433 fps
Vmin = 421 fps
Vmax = 454 fps
StDev = 10.4 fps
Krytox is better, but gun is still firing way lower than expected. I know "several hundred rounds" should be fired before the gun settles in, but it shouldn't be firing this slow out of the gate.
I'm suspicious of the springs. Took pictures, the inner spring is nearly 3/4" shorter than the outer spring. Looking at the Waffencenter site, their picture of the two springs is exact opposite - inner spring is actually longer than outer spring (if the photo can be believed). The ends of the springs look "factory flattened" so I don't necessarily suspect someone tried to re-use a broken inner spring, although someone skilled certainly could have re-flattened one end. New springs are on the way from ARH, and if I can ever figure out how to pay Waffencenter I'll have other 380 parts coming as well. The payment options on their site are lacking for those of us in the US (no credit card or PayPal options, only a "bank transfer" which I'll have to figure out).
Finally, ran Hector's "blow" tests and everything seems very buttoned up. No leaks, and the piston ring seems to be working great too (checked with piston inside compression chamber, blocked the breech seal hole, and pulled on the piston - piston sits tight, does not pull out of chamber at all).
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James,
I admire your determination. Do you really enjoy this?
I would have sent it off to PlinkAirguns, etc., a long time ago. :-[ ;D
-Y
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Ha! Well, I have about a dozen airguns, all springers, and even though I bought my first FWB 124 in 1979, in all these years I've never tried tuning one up. Always sent them off to the experts. In the case of the 380, Randy Bimrose. It's always bothered me that the gun came back not firing well, but it took me another decade to get up the courage to do a tear-down. Without Hector's help, it wouldn't have happened at all, as I had no idea which screws to focus on, and in which order. Turns out the 380 is super easy to take apart, aside from one element - the breech seal. The compression chamber has this black plastic ring around the front of it, I can't tell if it captures the breech seal of if the seal just pops straight out on its own. Randy had changed the breech seal and the gun hasn't been shot that much since, so I'm pretty sure that seal is still OK.
After watching all these YouTubers in DIY mode, I figured I could at least get the gun closer to spec with a clean-up. For whatever reason, the gun went the other way... even lower velocity than I was getting prior to tear-down. Haven't given up yet, I think the final straw will be when JM's spring set arrives (Friday). If new springs don't help, I'll likely be forced to send it into the abyss for an expert overhaul. The engineer in me is not ready to give up yet.
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James;
As things change, what used to be THE thing a few years ago, is no longer THE thing now. Moly is useful in sporters and more powerful guns where you actually WANT a "controlled" amount of dieseling to drive the power. Match guns operate, or SHOULD operate in the "Pop-Gun" regime where there is no dieseling. This is the most stable and consistent manner.
Krytox came onto the scene some years ago, after a couple of years Ultimox came into the market to solve some of the problems Krytox had. If you live in San Diego (I have a very dear Aunt there), then you do not need to worry about humidity.
What Yogi says is totally accurate, Moly can give you temperature variability that neither Ultimox nor Krytox will.
In any case, you are far ahead of the game because your previous numbers were obtained in the "internal combustion" mode, as the oil spit out by the gun told you.
MOST probably, the thin shortened spring is the culprit.
As small in diameter as this spring is, it is part; essential part, of how these guns work.
Consider that without the full length of that inner spring, the outer spring does not have a "guide" for a portion of its travels, vibrations occurring during these times will be energy lost to space. And without the full length, there is precious little energy that can be added by the smaller spring to the total output.
If the rifle passed the blow tests, you do not need to worry about the seals, and the only possible culprit left is that short inner spring.
One more question:
MY 380 has metallic inner guides (in reality it is sort of a tubular thing) inside the piston, but I have recently read of someone that says he has a non-metallic guide. This troubles me no end, because it means that there were two different production batches (at least) of the pistons, and given how complex those pistons are, it means that some guns are not worth what people think they are worth because it will not be long before those plastic guides start failing.
380's can be worth a LOT of money, I've seen them go from $700 to $2,000, it is well worth the effort to put yours back in shape.
Glad I have been able to help.
Keep well, shoot straight and keep us posted!
HM
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Thanks Hector,
Questions about the springs:
1) In your photos, you show a broken inner spring lying beside the outer spring. Photos can be deceiving, but appears your inner spring is also shorter than the outer spring? (even when I account for the small broken part)
2) Did you purchase new springs for your 380? If so, do you recall from where - JM, Waffencenter, other?
3) JM 380 springs will be here Friday, also ordering springs from Waffencenter (still working on bank transfer details)
Re: piston inner guide, mine is metal like yours.
Last question: do you know how to remove/replace the breech seal? My compression chamber has this black plastic "cap" at the breech end, and I notice in your picture this "cap" appears to be metal (is that right? Maybe another difference between model years). I'm unclear if that "cap" must be removed, prior to removing the breech seal - or if the breech seal just pulls straight out, passing through the "cap". Since this is a critical area of the system, I don't want to just pry off that black plastic cap without good understanding, as it could create a leak path if I gouge it.
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Anschutz Model 380 Disassembly:
1) Remove rear plastic end-cap 103 – see Anschutz photo #1 in disassembly instructions (see Hector's external link)
2) Remove the plastic collar 93 covering the breech – see Anschutz photo #2 in disassembly instructions
3) Remove Philips screw 95 from underside of receiver
4) At rear of cocking lever, make note of position of eccentric bolt 80. The bolt has a tiny dot that points towards a sprialgraph of lines. When re-assembling gun later, the dot should point at the same line as before disassembly
5) Remove e-clip (retaining collar) 82 from eccentric bolt 80, then slide/punch eccentric bolt out of its slot
6) Pull cocking lever 75 back as far as it will go, then remove cocking rod 76
7) Slide inner barrel/trigger assembly rearward, separating it from the outer receiver 92
8. Loosen the tiny 2mm hex screw 13, then remove trigger block mounting screw 14 from front of the trigger assembly
9) With cocking lever 75 still pulled back, remove screw 12 and abutment 11 from the RIGHT-hand side of the receiver. Note: cocking lever 75 is pulled back so this screw 12 can be accessed
10) Close the cocking lever, by sliding a thin screwdriver into the trigger assembly to disconnect pawl 38 from the cocking lever ratchet wheel 83. While pressing on the pawl, the lever should easily move forward. See Anschutz phto #4 in disassembly instructions. Sounds harder than it is - just drop a thin screwdriver down into the trigger assy, right next to the base of the trigger, and gently push down and forward (towards the muzzle) until you feel a little spring-loaded "pawl" down in there. Once you feel it, gently pressing on it will separate the pawl from the cocking lever ratchet, so the cocking lever will move freely. We want the cocking lever closed because we're going to put the receiver into a vise next. The cocking lever mechanism sits at the very rear of the receiver - when the cocking lever is closed, the rear of the receiver becomes "flat-ish" and creates a good surface for the rear vise jaw to press against
11) Clamp device in a strong vise; Anschutz estimates ~ 55lbs of spring force
12) Remove screw 12 and abutment 11 from left-hand side of receiver, near the rear. At this point, the trigger and spring are only held in place by the vise
13) Slowly back out the vise, making sure to hold onto the trigger assy to keep it straight as it slides out
14) The trigger assy remains as a solid block, while the two mainsprings (inner and outer), the piston, and the compression chamber will all separate into individual pieces
Easier than FWB 300 disassembly from what I've read/watched, no major "tricks' to learn here. Now if anything were to ever go wrong with the trigger assembly... that might be a chore to work on, as that thing reminds me of a Swiss watch. Lots of little pins/e-clips/springs/ and poor visibility into the inner workings.
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Thanks Hector,
Questions about the springs:
1) In your photos, you show a broken inner spring lying beside the outer spring. Photos can be deceiving, but appears your inner spring is also shorter than the outer spring? (even when I account for the small broken part)
2) Did you purchase new springs for your 380? If so, do you recall from where - JM, Waffencenter, other?
3) JM 380 springs will be here Friday, also ordering springs from Waffencenter (still working on bank transfer details)
Re: piston inner guide, mine is metal like yours.
Last question: do you know how to remove/replace the breech seal? My compression chamber has this black plastic "cap" at the breech end, and I notice in your picture this "cap" appears to be metal (is that right? Maybe another difference between model years). I'm unclear if that "cap" must be removed, prior to removing the breech seal - or if the breech seal just pulls straight out, passing through the "cap". Since this is a critical area of the system, I don't want to just pry off that black plastic cap without good understanding, as it could create a leak path if I gouge it.
James;
I thought I was clear in my posts that these pictures are NOT mine.
When I did mine, MANY years ago there weren't many digital cameras around and I was not in the habit of documenting as much as I am today.
I got three sets of springs from JM, checking them today, yes the smaller spring is also shorter.
Conical seals have a "lip" against which they should rest, otherwise they would pop out spontaneously.
In the sectioned drawing I do not see any ""collar" holding the conical seal, but it is an aspect of sectioned guns that some parts get lost.
What you describe as a black ring could well be a "collar" of some sort.
Again, if your gun passes the blow tests do not even consider changing the seals.
Apologies for the misunderstanding.
HM
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Thanks Hector, my apologies for the misunderstanding re: pics.
So the inner spring is shorter than outer spring… good to know.
Re: breech seal, the plastic outer ring must be the “lip” holding in the breech seal, as you noted. I won’t mess with it for now, seems to be fine.
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Received new springs from JM today. The inner spring is similar in length/turns to the old spring, but the outer spring is a full inch+ longer. I’m hoping this means that the old outer spring had taken a set and “shrunk”, reducing its power. Does that happen with these springs?
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Maddening. New springs went in with more force than originals, cocking stroke noticeably stiffer, yet velocity did not move at all. Still around 407 fps (3.0 fpe) with 8.2g Meisterkugelns.
Has to mean there is a leak path somewhere in the compression chamber. Breech seal looks fine, but am not 100% sure if it is - and don't know how to remove it.
Ordered new piston ring from Waffencenter, who knows when that will arrive. I'm utterly baffled.
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Maddening. New springs went in with more force than originals, cocking stroke noticeably stiffer, yet velocity did not move at all. Still around 407 fps (3.0 fpe) with 8.2g Meisterkugelns.
Has to mean there is a leak path somewhere in the compression chamber. Breech seal looks fine, but am not 100% sure if it is - and don't know how to remove it.
Ordered new piston ring from Waffencenter, who knows when that will arrive. I'm utterly baffled.
If there is a leak, it is not in the seals.
Blow tests are useful because at the low pressure that human lungs can provide, leaks are MORE apparent than at high pressures where the sound barrier acts as a leak-stopper in most pin-hole cases.
Questions that should have been asked before, but I overlooked them, I apologize for that:
Have you cleaned your barrel?
If you have, have you slugged the barrel with the pellet you are using?
Loose pellets can not only fall back into the compression chamber, but they will also yield lower energies.
There is a reason why H&N makes match pellets from 4.49 to 4.53, you would be amazed at how much the head size contributes to proper energy yield.
Just as an example: a short stroke D54 I am preparing yields 15.5 ft-lbs with the 9.56 Baracuda Hunter Extreme (4.52 head size), then it yields 13.5 ft-lbs with the H&N BFT (4.50 hed size), same weight of pellet, same alloy, same manufacturer.
I THINK the example is applicable because both guns (the 380 and the 54 in question) have short strokes and are extremely optimized to the "objective" pellet.
If you push a MK's through the bore and feel no, or very little resistance, then we have problem. If there is not enough "starting" pressure/force for the pellet to act as the "liberator" of the shot cycle, we have a problem. Slug the barrel with different pellets and note the difference in starting forces and friction drags along the barrel.
HTH
HM
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Thanks much Hector, I haven’t cleaned the barrel - will do. Re: the Meisterkugelns, I have noticed they are not the tightest fitting pellet. Will try slugging the barrel with them, and others , thanks for the great suggestion. I guess with this fixed side lever I’ll need to disassemble the gun to push the pellet through from the breech end.
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IDEALLY, yes, all rods should be run from the breech end with no spring load.
In the real world that is not always possible. In a well made barrel (like the Anschütz') you should have no problem pushing a pellet from the breech using a Swab-it:
https://www.swab-its.com/products/17cal-177cal-4-5mm-air-rifle-gun-cleaning-bore-whips-by-swab-its?variant=2561680323 (https://www.swab-its.com/products/17cal-177cal-4-5mm-air-rifle-gun-cleaning-bore-whips-by-swab-its?variant=2561680323)
The choke may be a bit of an effort, but this is my benchmark for a really good barrel. The constriction will be there, but the barrel will be finely enough made that a flexible "rod" is enough to push the pellet through.
Keep well and shoot straight!
HM
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If you do pop your breech seal out, be advised that there may or may not be shims present under the seal.
These shims are present on some rifles to adjust the height of the breech seal in its bore, which in turn adjusts the lock up of the rifle as the compression cylinder goes into battery. Basically it adjusts the squish of the seal to the breech end of barrel, which is determined by how much effort it takes to fully close the cooking arm until it latches.
There's a measurement for that squish factor, but I do not remember where I read it or saw it mentioned.
Hector may have input on that, and I would bet money on his guess over most others. Diana 54 experience should translate over to the 380 concerning the lock up effort on the side lever.
Edit-
The information is at the very end of the English language portion of the manual. Cocking lever pre stress is the technical term. 3mm is the number.
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Thanks Charles, manual does show a shim in the parts diagram, sitting right behind the breech seal. I don’t see the “3mm cocking lever pre-stress” anywhere in the manual? I’m referring to the manual link provided by Hector.
Still not sure how to “pop out” this seal… just pry it out using a small jewelers flat-head? This is how I’ve seen others removing FWB 300 seals. Or I could hook the center hole, but am concerned with damaging the spacer behind the seal. No experience with the Diana 54 (someday!).
The cocking lever has an eccentric bolt #80, which goes in a specific way - there’s a dot on the bolt that points to a spiral graph etched on the cocking lever. Manual says to remember where this dot points and return the bolt to the same position on reassembly, which I did. I wonder if rotating that bolt changes the lock-up effort??
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Page 16, bottom right corner. Tells you how to check and set pre stress on the side lever.
If you are set on changing out the breech seal, then I would work it out with a dental probe. Paying particular attention to not gouging or scratching the bore of the seal recess of course. There may be more than one shim under the seal, so eyes open on that aspect.
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Page 16, bottom right corner. Tells you how to check and set pre stress on the side lever.
If you are set on changing out the breech seal, then I would work it out with a dental probe. Paying particular attention to not gouging or scratching the bore of the seal recess of course. There may be more than one shim under the seal, so eyes open on that aspect.
Thanks, was fumbling around in the disassembly section. Breech pressure seems pretty spot on, also saw the eccentric bolt explanation on the next page. It does increase the pre-stress as I suspected.
After slugging and cleaning the barrel, and adjusting the eccentric bolt for more pressure, velocity has not moved. Examined the breech seal under a microscope, I can see where the seal meets the compression chamber wall (exit port). Appears there is no spacer. Won’t know for sure until I wiggle it out.
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Removed seal, using a hook tool, stabbed into the side wall of the seal. Pulled straight out, no "lip" or anything holding it in, and did not require a lot of force (I've read that other breech seals can be very tough to pull out). The new seals I have came from Lewis Reinhold via JM, and don't appear to require a spacer behind them.
I checked the pre-stress using the manual's instructions, the interference begins roughly 1/8" (3+mm) from level-lock, which seems to be per spec. I've also been advised to leave the gun closed in the uncocked position for 24-48 hours to help the seal form around the breech. Not sure how much that matters but will give it a try. First few shots, velocity was up but only marginally, around 420-430 fps. The fact it changed at all likely indicates some leakage around this seal area.
Since there was no spacer behind the seal, I also can't be 100% sure if a spacer is needed or not. I'm judging things based pretty much on the cocking lever pre-stress just prior to latching. With the old seal, I tried rotating the eccentric bolt #80 to more aggressive and less aggressive positions, and I did observe minor velocity changes (10-15 fps or so), nothing close to how the gun should be shooting but indicative of some sensitivity to the seal pressure I guess.
Lastly, on my compression chamber, the top is a single piece of hard black plastic as shown in the photo, encompassing the entire top of the chamber. On other photos (Hector, et al) I've noticed this top section may be metal. Perhaps indicates a change in production at some point, or the pics I've seen are faking me out.
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My compression tube looks identical to yours.
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Jim;
Glad you are dealing with this ONE STEP at a time.
It is immensely useful to the community. THANKS!
My compression chamber looks like yours.
I am sure there were several production changes along the history of the rifle. Sectioned models are usually made with pre-production or very early production models and almost always are used as training aids.
We need to remember that in Germany adding or removing METAL from a gun by an unlicensed gunsmith carries a hefty legal penalty. So if some parts are made of plastic, that makes maintenance easier for the user.
Therefore factories made sure that factory reps travelled with the sectioned models all around the country showing gunsmiths how to deal with their guns.
An old rep I know from past IWA's, told me that in a year, he would drive over 200,000 kms to cover all his "visits"; in one year, he had his engine completely overhauled TWICE. Of course this was many years ago, before re-unification.
For Germany, that would be like an American driving a million miles a year.
How history has changed.
Thanks again, and keep us posted!
HM
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Thanks Hector, interesting history note re: the plastic outer section. This has been quite the learning experience overall.
Yesterday I looked closely under the microscope at the compression chamber, piston, and piston ring. There is very minor scratching toward the rear of the piston in one spot, I mean very minor as in 0000 steel wool-type faint marks. I considered running some 1200 grit wet/dry over the piston surface, but I can't image such small marks at the rear of the piston would really matter. I polished the compression chamber using only a dry cotton wheel attachment (no polishing paste or lube of any kind), to a mirror finish with no hint of any scratches/blemishes inside. Looks gorgeous. I examined the piston ring very carefully, it was darkened from years of whatever, so I ran it over a 1500 grit wet/dry pad to restore it to its shiny original condition (outer edge, inner edge, and both sides). After all that, I applied a tiny amount of krytox around the piston ring only, and reassembled. I wanted to see if a "dry" compression chamber with only a tiny amount of krytox on the piston ring might work out better. It didn't. Same poor velocity in the low 400's.
WCG items have shipped, including a new piston buffer, breech seal, piston ring, and inner/outer springs. I will compare those to the parts I obtained from JM.
Read/watched a bunch of Paul Watts stuff last night, was intrigued by his frequent comments that compression chambers are often in need of honing to correct for tapering/out-of-round/etc issues. He noted drops of over 100 fps on some guns with poor chamber integrity. This gun did shoot around 510 fps with 8.2g prior to disassembly, so I don't think the chamber is that far off or else the gun never would have shot in the 500's. Still, given everything else I've changed (literally everything except the piston ring), does lead me to wonder if there's something like this afoot.
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I would be very surprised if the problem was due to an out of round compression tube. My bet at this point would be on the compression ring being out of spec.
The FWB 300 uses a similar compression ring on its piston, and there is a measurement or assembled dimension to check allowing you to ensure that it is in tolerance, and the allowable variance is very small. I have not been able to source a similar dimension for the ring in the 380 allowing me to be able to check my own, or to provide a figure for you to check yours unfortunately.
I will keep looking, and if I come up with anything the information will be posted in this thread so all this good 380 info can be archived for future reference.
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Thanks Chuck, a new piston ring is now en route from WCG, should be here in the next week or less.
Re: the ring’s spec, dumb question: if I measure the outer diameter of the ring with the open end closed down, should that diameter be equal to, or just slightly less than, the compression chamber’s diameter? I assume the critical spec is with the ring perfectly closed, otherwise air would leak past the gap.
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As far as I can remember, the critical dimension of the piston ring is the cross sectional thickness, measured from inner to outer bearing surfaces.
This measurement does directly affect the end gap of the ring when it is installed, which in turn affects how much bypass the ring will allow under compression.
I do remember a post from the past where one fellow had a piston ring that was .001 or .002 out of spec, and it did affect the MV of the rifle, verified over a chrony. The specific numbers escape me, but the message went into the mental rolodex as an area to check when addressing an unexplained drop in power not rectified by a new breech seal.
The piston ring bypassing air also becomes an issue when these type of rifles are grossly oversprung in an attempt to gain more FPS for various reasons..
Once your new piston ring is in hand, I would definitely check the cross section of new VS old. This should give you an immediate indication of whether your currently installed piston ring has worn and is bypassing.
If you would be so kind sir, please share your measurements and findings with the collective so that we can all benefit from the information.
Edit-
Later today, I will record a 10 shot string from my 380 with RWS Hobby and RWS Meisterkugeln pellets to give you a baseline, goal, target velocity to aim for.
Rifle has approximately 3k pellets through it after a full refresh, including new piston ring.
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Ooohh, Chuck, now you've gone and done it!
You MADE me get my 380 out and have a chrono session! LOL!
Actually, both, her and me needed the exercise.
;-)
Chronoed a dozen pellets, but the really noteworthy would be:
1.- RWS MK's.- 680 ± 2 fps
2.- QYS Olympic.- 653 ± 6 fps
3.- Eley Ventus 4.50.- 577 ± 2 fps
4.- H&N FM 4.49.- 621 ± 3 fps
5.- GTO.- 670 ± 7 fps
And just for the sake of completeness of the thread:
Here is my breech:
(https://imagizer.imageshack.com/v2/800x600q90/924/Xehm8u.jpg)
My rear sight:
(https://imagizer.imageshack.com/v2/800x600q90/922/bEVWHA.jpg)
Right side of gun:
(https://imagizer.imageshack.com/v2/800x600q90/922/p6iMkc.jpg)
Left side:
(https://imagizer.imageshack.com/v2/800x600q90/923/SJXodH.jpg)
S/n is 0203XX, so it is not an early model.
I did realize that my breech closing pressure is on the light side, but the gun passes the blow tests easily and the MV's are good, so I will not mess with it.
HTH, keep well and shoot straight!
HM
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Thanks Hector and Chuck, what a treasure trove this forum is.
Chuck, will do re: PR measurements. DHL hasn’t updated status so it’s looking like next week.
Hector, those are great numbers, gives me hope!
Do either of you recall how you lubricated the piston and chamber? I’m on the krytox train at the moment, the ultimox I ordered is delayed in transit. Also purchased a tube of Super Lube per Lewis Reinhold, haven’t tried it yet. Specifically interested in how much is applied, as I keep reading that bone dry or minute quantities are best for these 10m power plants. I applied krytox and then wiped it off, assuming an invisible thin trace amount would be left behind. Not sure if this is the proper technique.
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Very small amount of lubrication in the compression cylinder is the watchword on these type of rifles.
Too much viscous lube will actually slow them down, while too much of the incorrect lube will also lead to dieseling.
I would go Krytox myself, and apply very sparingly. I use an artists paint brush to apply a small amount around the interior circumference of the open end of the compression cylinder. I then insert the assembled piston and cycle it full length a few times to distribute the lube. I then remove the piston and examine both pieces for any sign of excessive lube, such as a small deposit or build up, and remove that. Reinsert and cycle until things are all slicked up with no evidence of excess, and call it good enuff.
A very very light film is what is desired.
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My chrony results are slightly different from Hectors, but not off by much....
RWS 8.2 gr. Meisterkugeln in 4.51head size averaged 620
RWS 7.0 gr. Hobby in 4.53 head size averaged 640
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Thanks Hector and Chuck, what a treasure trove this forum is.
Chuck, will do re: PR measurements. DHL hasn’t updated status so it’s looking like next week.
Hector, those are great numbers, gives me hope!
Do either of you recall how you lubricated the piston and chamber? I’m on the krytox train at the moment, the ultimox I ordered is delayed in transit. Also purchased a tube of Super Lube per Lewis Reinhold, haven’t tried it yet. Specifically interested in how much is applied, as I keep reading that bone dry or minute quantities are best for these 10m power plants. I applied krytox and then wiped it off, assuming an invisible thin trace amount would be left behind. Not sure if this is the proper technique.
GrandMa would say that "Half of the getting is in the asking"
This forum is, mostly, civil and helpful because most readers do the same.
The small bunch of us that write a lot, really depend on those that don't.
;-)
And there, you have done it again! LOL!
Had to go back 4 notebooks to 2012 to remind myself of what I did.
I surprised myself: I used T-9.
T-9 is a bike chain lube that I use for pellets. It goes in liquid, but it dries and becomes a semi-solid. Originally designed by Boeing for the lubrication of the electrical parts of Jet Engines, it will not burn or diesel.
My notes say that I cleaned with lacquer thinner, then applied T-9, then wiped off and allowed to dry overnight.
At present I would use Ultimox just because I have access to the oil as well as the grease and that simplifies my life, plus the fact that Maryland is extremely humid in summer and Ultimox is not as hygroscopic as Krytox, but I guess that Ohio and California do not have that problem.
Chuck's method is more than correct: apply (I use my pinky finger), wipe off, then put all the parts together and work without a spring, then wipe again and assemble.
A note here is important:
On the very early versions, Anschütz and FWB used a "wavy cut" of the bronze rings, meaning they were turned to dimension and then jig-saw cut by hand.
This made the rings, in effect, "labyrinth seals" where the seals seal precisely using the sound barrier to block the "escape routes" of the air.
In modern times, high end compressors also use this method but, in pieces of machinery that are worth several tens of thousands of dollars, that is understandable. A more modern method is to supercool (as in liquid nitrogen) the ring and break it off in one part, the parts will mate perfectly and will not allow any gas to escape. Again, this is predicated on a perfectly uniform compression chamber.
At some point in time, it would be interesting to replace these old bronze rings with Teflon and see how things work. My experiments with Teflon ORings in the 54 have yielded great results efficiency-wise, BUT the shot cycle is horrible because those pistons don't have a buffer.
Anyway, keep us posted!
HM
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Thanks Chuck and Hector for dusting off the notebooks and for taking your 380's for a spin!
Lube methods I used were similar but not identical. I tried a couple of variations, both times after running the piston and compression chamber through an ultrasonic bath using Simple Green/Distilled Water.
1) Using a swab, squeezed a droplet of Krytox onto the swab and ran it around the compression chamber, about half-way down. Ran a second dry swab through to remove any excess, then looked under a microscope to confirm no blobs or excess. Then ran a droplet around the piston ring, and wiped it clean. Then a final droplet around the base of the piston, wiped clean again. When wiped, the Krytox is practically invisible, which makes the amateur (me) endlessly wonder if it's enough.
2) Squeezed a small Krytox droplet onto the piston ring, and ran it around the circumference, then wiped it clean. No other lube applied.
The very first attempt I made was with ARH Moly paste, since Moly was clearly used in the gun previously. Similar approach, very sparse amount, barely visible when done.
Of course, none of these has made a hill of beans' worth of difference, I'm in the low 400's. And so I wait impatiently for the WCG care package.
When my new piston ring arrives, do I need to do anything special with it, or the installation? My assumption is that the ring should not need any polishing, and the installation should occur over the front end (piston buffer end) by gently pulling the ring apart to just BARELY get it over the piston OD, then slide the ring into its slot. I read that these rings can be "delicate" but seems to me they're pretty stout, unless one did something excessive like applying opposing forces to each open end, or unduly pulling the ring "apart" for easier installation. My plan is to go very slow with this new ring, and apply just barely enough force to get it around the piston face.
Another thing I've been wondering... velocity dropped nearly 100fps after initial tear-down, and the ring was not removed. However, it may have been rotated during clean-up/new Moly. Makes me wonder if the ring's exact rotational position needed to be recorded when I tore it apart, to account for any eccentricities in the chamber that the ring may have worn down to accommodate. I didn't think to do that. Guess I'm trying to understand how a simple tear-down/cleanup/re-lube can impact the gun so much, to the point that it never comes back to original velocity. I have a lot to learn...
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The new ring should need nothing other than to be installed.
The method that you describe for installation mirrors my own method exactly. Slow and steady being the watch words for re installation of course, but you demonstrate that you are already on point in that regard. The ring is delicate in the regard that it will not flex or distend a great amount, but it will most definitely have enough flex to pass over the nose of the piston and slide back to seat in the groove.
In reference to your unexplained loss of power, the only point that I can bring up is earlier in this thread you mentioned that you polished or lightly cleaned up the piston ring. If your rifle was already running a little on the light side of the power curve, perhaps your piston ring was ever so slightly worn and by polishing it you may have inadvertently removed enough material to reduce it further. That is just a guess, based on the fact that you have basically refreshed all of the internals relevant to power production with the exception of the piston ring.
I have never read, seen, nor heard mentioned any special orientation of the piston ring coming into play. Not in any Anschutz manuals, nor in any tutorials on tear down and rebuilds on Anschutz or FWB rifles using the piston ring set up. That includes several lengthy discourses on rebuilding those rifles on foreign language sites, and conversations throughout the years.
Barring the piston ring being the cause, we come back to the compression cylinder being eccentric or out of round. I would be very surprised to see that in an Anschutz product, and can not recall ever hearing of an Anschutz or even a FWB compression cylinder being found to be out of round. If we were discussing a Diana or Weihrauch, that may be a real possibility, but at the level of production of gold medal winning 10 meter match rifles, I believe that it would be a very rare finding if such is the case.
Such an occurrence would necessitate the procurement of a new compression cylinder I believe, because honing yours into concentricity would necessitate an over sized piston ring to seal properly, and good luck in that regard.
If that 'worst case' scenario rears its head, my recommendation would be an urgent plea to our friend and fellow contributor Hector as to what his thoughts were on remedies. It is possible that the world's first HMO piston equipped Anschutz 380 may be a possibility..
Regards to you Hector, you never fail to share useful insights and experience, and always do so freely.
Edit-
My reference to using Krytox was erroneous, I should have said Ultimox, as that is what I use exclusively. I can get Ultimox far cheaper that Krytox, and it does have corrosion resistant properties. If you have Krytox on hand, then by all means use it and do not feel like you are missing the boat. It will work just fine.
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James,
I do not believe that your method of cleaning, Simple Green and a sonic bath are insufficient to remove every last little bit of Moly lube, and you need to remove every last little bit of moly for Krytox/Ultimox to work properly. It will mix with your synthetic lubes and gum everything up. You need to reclean everything. IMHO.
-Y
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Thanks Chuck for the great info. Long thread, so I’m sure I’ve caused a bit of confusion. The first time I disassembled the gun, I removed the pellet that had smushed inside the chamber, gave the chamber and piston and springs a bath, changed the piston buffer, and re-applied Moly. The ring was not touched at all, except for maybe some rotation during cleaning. On reassembly, the gun shot 100 fps lower, roughly 409-410 fps. On later disassemblies (third or fourth try), I finally polished the ring, but only using 1500 grit wet/dry and just enough to eliminate the discoloring. With Krytox, polished ring, new buffer and new seal, power came up slightly, roughly 410-420 fps vs 400-410 fps. Sorry for confusing info.
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Thanks Yogi. The first time I cleaned the parts, I re-applied Moly and the velocity dropped 100 fps. The krypton was applied after a subsequent cleaning. Re: gumming up, is this at a microscopic level? Because I’m only firing a few shots to check velocity (10-20), and there is no visual evidence of any gumming. I used simple green based some others who reported success with it but am happy to try something else. Hector mentioned lacquer thinner… others have mentioned brake cleaner. Suggestions?
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James, I know it sounds silly, but you should not forget that your rifle was "Spitting oil" at first.
Large amounts of oil, even if they do not contribute to the energy yield through dieseling, will contribute to energy yield by ensuring a proper seal between piston and cylinder.
IF this assumption is correct, then replacing the ring should solve the issue and you should have a perfectly functioning 380.
If it doesn't, then perhaps we have found the reason why previous owner/tuner delivered the rifle with lots of oil.
Now, to be somewhat rude, I would then doubt the intensity of the "blow tests" you performed, because I have never encountered a seal that would pass the blow tests that would then need replacing. There is always a first time, so whatever happened, we'll live and learn.
NO factory is above the creation of a lemon. The VERY high end ones will detect the lemon before it goes out to the public and re-work it till it is correct, OR disassemble it completely and use the parts.
At the height of the Olympic Match Spring-Piston rifles, when everyone was starting to go to SSP (pioneered by Walther), Anschütz MAY have "loosened" their hold on QC to make the transition easier for them.
Still, in the same way that people find spare parts for old cars, I am sure that somewhere there is a perfectly good compression chamber in a battered and useless rifle that was abandoned in an old barn as a doorstop.
;-)
On your method of cleaning and lubing, the ONLY thing where I would deviate would be using a strong solvent instead of simple green as a degreaser.
For the newer projects I am using industrial acetone, and in some cases Xylol. These two actually dissolve plastic and they do dissolve the Teflon films that are formed by Ultimox and Krytox. They are also excellent degreasers.
Once used, I use them as weed-killers in my paved pathways, I use so little that all my pavers have weeds anyway. LOL!
Keep the faith and let's go into the last trench.
HM
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Thanks Hector, I went back to your blow-test instruction and I don't think I did the second test correctly. In fact, re-reading the instruction, I think I need a little more info in the second test:
"Would be pretty strange, but is the bronze ring good? Do the same blowing test with a de-sprung gun in the COCKED BUT NOT LOADED position."
- By "de-sprung", do you mean - the gun disassembled, springs removed, then re-assemble without springs?
- By "cocked but not loaded", do you mean - pull sidelever back to cocked position, return sidelever to closed, as if ready to fire (with no pellet of course), all with no springs in the gun?
If this is the test, I definitely need to repeat it.
Thank you again for so much patience, I would have given up long ago without this great advice.
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Not that Hector or Yogi need any affirmation from me, but those suggestions about cleaning are spot on.
You will be essentially starting from square 1 with a new piston ring and a properly prepped compression cylinder. No cross contamination or the like.
Hectors thoughts on the over oiled condition causing the existing ring to seal better are the most plausible explanation of the loss in power.
If nothing else, this thread is probably the most interesting discussion that I have had for some time. I love older 10m rifles, and the 380 is arguably the pinnacle of the coil sprung match rifle era.
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Thanks much Chuck. I’ll give ‘er a good cleaning when that new ring arrives. I will note again that after the first cleaning I reapplied Moly (not PTFE) with similar poor result. So not a cross-contamination issue for the first run. I hear the concern with simple green but felt the parts were super clean after a 20 minute bath. I would think cross-contamination would show by way of clumps or balled up PTFE/moly, but honestly I saw none of that - hence my question whether this is a microscopic-type thing. Nonetheless, this time I’ll try acetone or paint thinner or lacquer thinner (have to see what’s out there in ye ol’ shop), to remove that variable completely.
Your note about enjoying the thread brought such a smile, my wife had to know what the joker grin was all about. So glad to read that, I’m asking a lot of naive questions and really appreciate all the expertise.
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Thanks Hector, I went back to your blow-test instruction and I don't think I did the second test correctly. In fact, re-reading the instruction, I think I need a little more info in the second test:
"Would be pretty strange, but is the bronze ring good? Do the same blowing test with a de-sprung gun in the COCKED BUT NOT LOADED position."
- By "de-sprung", do you mean - the gun disassembled, springs removed, then re-assemble without springs?
- By "cocked but not loaded", do you mean - pull sidelever back to cocked position, return sidelever to closed, as if ready to fire (with no pellet of course), all with no springs in the gun?
If this is the test, I definitely need to repeat it.
Thank you again for so much patience, I would have given up long ago without this great advice.
Sorry, James, but yes, you need to repeat it.
The idea behind performing the blow test (and I do mean blowing with ALL your might), with the piston in BOTH positions (all the way forward and all the way back in the compression chamber) is to see if there is any conicity to the chamber itself.
When the blow test shows pass-through with the piston in the fired position, the "leak" can be in the breech seal (90% of the times), but it can also detect a compression chamber that is conical in the worst possible way (opening up towards the end of the shooting stroke).
If the blow test detects a compression chamber that is wider at the rear (pass-through with the piston in the cocked position), then there MAY be ways to remedy the situation, using synthetic seals.
So, the blow tests, as "simple" as they are DO provide valuable information for three possible problems:
Bad Breech sealing
Bad Piston sealing
Bad Compression chamber.
BTW, when you are about to (just before) install the new ring, PLEASE, take the following measurements:
1.- OD of piston to the BOTTOM of the groove
2.- OD of piston to the TOP edges of the groove(front and back, they MAY be different).
3.- WIDTH of groove.
If we need to think of synthetic seals, these measurements will be invaluable.
Just a precaution. I do think that the new ring will help, but it's an "ounce of prevention vs. a pound of cure" thing.
Keep well and shoot straight!
HM
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Thanks Hector, OK repeated the blow tests in both piston positions (forward and back), and could not detect any leak at all.
To be more "sure", I tuned my air compressor down to about 15 PSI and applied its rubber-coned tip to the barrel in both positions and again, could not detect any air leaking from the breech area or rear of the gun.
Further, I disassembled the gun once more, and checked the piston/chamber combo using compressed air at the transfer port, and even the slightest compressed air pushes the piston directly back with force. I am unable to hold the piston in place with any appreciable amount of air into the TP.
Not a scientific test, so not sure what to make of it. But seems like the existing piston ring is doing reasonably well. This is probably where an expert like yourself can tell the difference between "just OK but leaky" and "good".
Still waiting on WCG package, it's now being "processed by Customs" in New York...
Also took a look at pre-loading the springs a little, to see if velocity improves. Considered a spacer behind the rear guide but since the rear guide sits right on top of the trigger sear (amazingly tiny clearance), that won't work (sear wouldn't be able to engage piston). Could add a spacer in the piston itself but that just adds weight to the piston - counteracting the increased spring tension benefit by TBD amount. Plus, that piston has a funky internal design with a built-in inner spring guide, so any spacer has to be a custom-cut doughnut. Strike two.
Lastly, a general question: If I hold the compression chamber up vertically with the piston inside, should the piston fall out on its own very easily? It doesn't. It just sits there.
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Lastly, a general question: If I hold the compression chamber up vertically with the piston inside, should the piston fall out on its own very easily? It doesn't. It just sits there.
Not in my experience.
At least ¼ # to ½ # of force should be needed to move a properly sealing piston.
MOST OEM pistons weigh between 200 and 350 grams, and those that weigh more are high power sporters with parachute seals, so they usually need a bit more than 400 grams of force (about 1#) behind them to start to move.
Your blow tests seem to me to be spot on, so I am really starting to worry.
Once we are past the new sealing ring without success, the ONLY thing we would have not explored is the diameter of the TP.
Messing with the TP in a gun of this level would be the most heretical/asinine action I would expect, but ¡hey! people always surprise this old gunsmith....
It would also explain finding the pellet in the compression chamber. Since we have no way of finding out what pellet it was that fell BACK, it could easily have been one of the more common pellets falling back on an unusually large TP.
Went down to the gun room, took out my 380 and tried, to the best of my abilities, to measure the TP without disassembling using numbered drill shanks, it would seem to me to be between 4.35 and 4.25 (that's above #18, but under #17).
Which would preclude ANY normal pellet from falling BACK into the compression chamber, but, we found one there, so this now opens as a new possibility.
Try to check your TP and see where you are at.
Even a "rough polishing" of the TP could have created such a mess.
Hope everything returns to normal with the new ring seal.
Thanks for persevering on this!
HM
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Thanks very much Hector for the info. My 380 is apart so I've got full access to the compression chamber. It has a new breech seal so I've left it in place. Under the microscope, I can see the breech seal TP lines up perfectly with the chamber's TP, the two diameters are basically identical.
I have a total of 5 breech seals, obtained from Lewis Reinhold (who obtained them from JM). Measuring the seal TP's using transfer punches and a micrometer, I estimate the sizes as:
Seal #1: 4.71mm (this was the original Reinhold seal, removed as part of this rebuild)
Seal #2: 4.80mm (best estimate - the 4.76mm 3/16" bit bounces freely inside the hole, guesstimating the overage by looking under a scope)
Seal #3: 4.80mm (same as above)
Seal #4: 4.80mm (same as above)
Seal #5: 4.65mm (this one is in the compression chamber)
The compression chamber, measured from the inside, is also ~ 4.65mm.
Pellets fall easily through the holes of Seals #1-4. I've tried half-dozen different pellet types, it's obvious these seal's TP's are bigger than most any .177 pellet on the market. Which makes me wonder if these seals are even usable.
When I drop a MK pellet with skirt 4.65mm into the compression chamber TP from the inside, it falls through about mid-way and just barely catches on the skirt. Similar result if I drop a pellet into the chamber from the breech seal side - pellet falls mostly through, barely catching on the skirt.
Double checked my MK pellet head and skirt sizes against this reference, in close agreement: https://www.straightshooters.com/pellet-comparison.html (https://www.straightshooters.com/pellet-comparison.html)
All of these measurements are well above your estimated 4.25-4.35mm. So... "dang". I don't know what to make of this now. The breech seal TP's match up closely with the chamber TP, which makes me think the seals are roughly "correct". But since all of these are larger than most pellets, in contradiction to your gun and your assessment that the TP's should be smaller than any pellet, seems something is very wrong here. Perhaps we've narrowed in on the root cause.
If the TP is indeed too large, that would seem to be unfixable and require a new chamber/piston combo altogether. No idea where I'd obtain something like that, WCG doesn't sell such parts.
Aside - transfer punch kit, have found so many uses for it: https://www.amazon.com/gp/product/B01ADBNEJE/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 (https://www.amazon.com/gp/product/B01ADBNEJE/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)
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The breech seals are 16mm OD. One idea I'm mulling - slip a 16mm round brass shim right behind the breech seal, sandwiched between the breech seal and compression chamber. Found some 16mm brass shims that are only 0.4mm thick on Amazon. Am thinking to drill a 4.3mm center hole in one (average of Hector's two measurement numbers), and slip it in behind the breech seal as a poor man's way of resizing the TP diameter.
The barrel breech of this gun is cone-shaped, and reaches almost all the way to the compression chamber TP, because the breech seal is hollowed out to nearly the very bottom. In other words, the effective "length" of the TP is pretty small already, no more than a couple of mm's. So I'm thinking that a brass shim, although only 0.4mm thick, might be good enough to act as a TP substitute.
The 0.4mm will move the breech seal forward by 0.4mm, which will increase the seal pressure slightly in the closed position. I should be able to compensate for this by simply rotating the cocking lever eccentric bolt a little in the "less tension" direction, to hopefully keep the breech seal pressure roughly constant.
Is this nutty?
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I am so, so, sorry James.
Clearly someone with absolutely no knowledge, little understanding, and even less common sense decided that "mo' 's betta" and took some tool to the compression chamber, though I may be wrong on this, it does seem to be the most plausible explanation.
The TP size I "estimated" came not from the seals, but from steel TP UNDER the seated seal. With the gun cocked and the piston slightly retracted by pushing the lever a few degrees forward.
Your idea of the insert is EXCELLENT and, I think, merits a test. No need to change the breech seal for this test, use the same one you are using. 0.4 mm's thickness would seem to be sufficient to stand to use and thin enough that the locking pressure can be adjusted at the eccentric on the cocking lever.
You will find that drilling controlled holes in very thin metal is tricky. The best way I have found is to sandwich the metal sheet/piece between two scraps of oak or other really hard wood (hickory/maple) and that seems to work well.
Good job so far! Keep us posted!
HM
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Thanks Hector, brass shims should be here later today.
Looking at your earlier cutaway diagrams again, I ran the chamber picture through Topaz Gigapixel AI (via Lightroom) to improve the photo's clarity. In the photo, the compression chamber's TP diameter is same or just slightly larger than the bore diameter, i.e., 4.6mm or so. The breech seal TP hole also appears to match the compression chamber TP. This photo looks pretty much spot on with how my gun is configured.
I removed the breech seal w/ hook tool, and re-inspected the black "top cap" of the compression chamber. The black top cap is metal, not plastic as originally reported (sorr for confusion). The top cap is actually a solid milled piece, whose floor is the actual TP wall. The top cap drops down inside the chamber and is soldered/welded directly to the inside of the chamber wall. I can see this inner lip of the top cap from inside the chamber. On the cutaway (directly below the end of the barrel breech), I can see a gray/black round solder/weld joint holding the top cap to the chamber, and just to the right of that is what appears to be a metal ring of some sort, maybe for added support.
In theory, if there was some way to remove that top cap without damaging/destroying the chamber, I could take that top cap to a machine shop and have a new one made with a smaller TP hole size, then have it re-soldered/welded/whatever. Guessing the chamber would need to be heated by a torch or equivalent to work lose the solder/weld joint. Not sure if that "ring" I see in the cutaway near the solder joint would make this task harder or impossible.
Inspecting the chamber TP hole itself, if someone modified this TP they did a clean job because the TP looks perfectly smooth and centered, even under a microscope with high magnification. I researched the TP sizes for some other guns I could find in the forums, believe the largest I saw was around 4mm. So this large 4.65mm hole is a real head scratcher.
In another pic below, a Gamo Match Diabolo is dropped perfectly into the chamber TP hole. The pellet skirt measures 4.66mm, in pretty much exact agreement with yesterday's measurement.
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Thanks Hector, brass shims should be here later today.
Looking at your earlier cutaway diagrams again, I ran the chamber picture through Topaz Gigapixel AI (via Lightroom) to improve the photo's clarity. In the photo, the compression chamber's TP diameter is same or just slightly larger than the bore diameter, i.e., 4.6mm or so. The breech seal TP hole also appears to match the compression chamber TP. This photo looks pretty much spot on with how my gun is configured.
I removed the breech seal w/ hook tool, and re-inspected the black "top cap" of the compression chamber. The black top cap is metal, not plastic as originally reported (sorr for confusion). The top cap is actually a solid milled piece, whose floor is the actual TP wall. The top cap drops down inside the chamber and is soldered/welded directly to the inside of the chamber wall. I can see this inner lip of the top cap from inside the chamber. On the cutaway (directly below the end of the barrel breech), I can see a gray/black round solder/weld joint holding the top cap to the chamber, and just to the right of that is what appears to be a metal ring of some sort, maybe for added support.
In theory, if there was some way to remove that top cap without damaging/destroying the chamber, I could take that top cap to a machine shop and have a new one made with a smaller TP hole size, then have it re-soldered/welded/whatever. Guessing the chamber would need to be heated by a torch or equivalent to work lose the solder/weld joint. Not sure if that "ring" I see in the cutaway near the solder joint would make this task harder or impossible.
Inspecting the chamber TP hole itself, if someone modified this TP they did a clean job because the TP looks perfectly smooth and centered, even under a microscope with high magnification. I researched the TP sizes for some other guns I could find in the forums, believe the largest I saw was around 4mm. So this large 4.65mm hole is a real head scratcher.
In another pic below, a Gamo Match Diabolo is dropped perfectly into the chamber TP hole. The pellet skirt measures 4.66mm, in pretty much exact agreement with yesterday's measurement.
You make me wonder if what you have is a VERY early production model and thereby more closely corresponding the sectioned gun.
I think it is hard to measure things in pictures, but clearly, you have more experience there.
All models change over their life-cycle; some more, some less. The TP COULD have changed and, if so, then there should be two (or more) types of compression chambers.
In any case, let's see how the shim idea works.
Keep well and shoot straight!
HM
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Thanks Hector. Gun S/N is 09077. Read somewhere that an estimated 15,000 were made, but I don't know where the serial numbers started. Mine has the plastic cheek piece, which I thought came later on.
Practical problem with shims - my drill index goes from 5/32" to 11/64" (4.97mm to 4.36mm). I'll probably have to use the smaller bit and see if I can ream it out a little at a time. Tricky with 0.4mm thick brass shims, they're pretty flimsy.
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Prepped two brass shims, with center holes 4.0mm and 4.2mm. No difference between the two, overall velocity average still right at 400 fps (10 shot average), 2.9fpe, spread of 376-408 fps.
I notice that about 1 out of every 8-10 shots is markedly lower velocity than all the others. If I throw out the 376fps reading, the spread drops from 32fps to about 17fps. This was happening prior to the shims, so nothing new.
With gun apart, degreased using acetone and applied Ultimox 226 this time. Whatever is wrong with the gun, it's not the lube... have tried moly, krytox, super lube, and ultimox, all with pretty much exactly the same result.
Have exhausted all avenues I can think of at this point, except for piston ring replacement. New piston ring is still "in transit" somewhere in US, no estimated delivery date available from USPS.
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Success!!!!
WCG parts arrived today, pretty much every part is different geometry than the ARH parts I was using. Breakdown below, along with some photos. Summary:
- WCG springs are both significantly longer and have more tension
- WCG inner spring is longer than its outer spring, ARH is opposite
- WCG piston buffer is a full 2mm shorter than ARH - essentially the ARH piston buffer was short-stroking the system by 2mm
- WCG piston buffer BARELY clears the top of the piston - appears to be super accurately fabricated, less than 1mm clearance all around the rim of the piston, impressive
- WCG breech seal is over 1mm taller than the ARH, with a much bigger transfer port hole as well (5.5mm!)
The piston rings are very similar, with the WCG being a little thinner than the OEM piston ring (I bought the gun used so can't be sure if this is the original piston ring or from someone else).
I lubed only the following, using Ultimox (everything was degreased using Simple Green in an ultrasonic bath, followed by paint thinner by hand):
- Piston Ring (roughly a 2mm drop, spread around the perimeter)
- Inner spring ends (similar amount)
- Outer spring ends (similar amount)
Installation notes:
- WCG piston buffer took tremendous force to install, unlike the ARH buffer. I have no idea how I'll ever replace it, will literally have to dremel it out because there is zero lip to work with to pry it out
- WCG breech seal also took tremendous effort to install, even worse than the piston buffer. Same story, that thing will never come out without destroying it.
- WCG piston ring actually went on easier than OEM, a lot easier. Interesting. Under a microscope they look pretty much identical.
First 10-shot group, using RWS Meisterkugeln 8.2g wadcutters:
- Velocity (avg) = 590 fps
- Energy (avg) = 6.33 fpe
- Min speed = 581 fps
- Max speed = 602 fps
- Spread = 21.6 fps
- Std Dev = 6.6 fps
This is much more in line with expectation for this gun. In the past I had found owners who were getting right around 600 fps w/ 8 grain. With 7 grain I expect this will hit 650 fps or so.
Huge THANK YOU to Hector and Chuck, who stuck with me through this anguish.
Conclusion: the right parts make all the difference, and in this case WCG definitely had the right stuff. Couldn't be more pleased.
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Remaining pics:
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OUTSTANDING!!!!
I was rooting for you man, and it looks as if your perseverance has paid dividends.
I clammed up for a bit because you were solidly in Hectors zone talking about transfer port adjustments. My input was exhausted somewhere back around piston ring replacement!
590 is right in the butter zone, and you may gain a smidgen as the new set up beds in.
Happy day today, I am as pleased as punch to hear that you got it up and running in spec..Congratulations on a successful work through, and thanks for the direct comparison of the ARH and WCG spares. That is EXCELLENT info for the Anschutz 380 archive.
Now go enjoy the finely crafted fruits of German engineering!!!
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Woohoo! Thanks so much again Chuck for all the advice. Can't tell you how happy I am after struggling with this for weeks.
As an unbelievable bonus, I pulled out my A380 parts box (DeWalt parts organizer thingy) and mounted the original Anschutz front/rear diopters; front has a clear annular ring insert which I love. Those sights have not been on that gun in 10 years, almost to the day.
Never saved any marks on the gun for re-mounting these, I just slapped them on and adjusted the rear back and forth until it felt good.
Below is the very first 10m benchrest shot I took, with an RWS Meisterkugeln 8.2g. VERY FIRST SHOT!!! I have never in my life had this happen when re-mounting sights of any kind (scope, diopter, open, peep...). I literally almost started crying I was so happy.
The gun is firing just beautifully, no recoil at all, butter smooth, trigger is dialed in, man I am just in heaven. And the pellets are hitting hard, like my FWB 300's. There is a massive difference between 400fps and 600fps - a THWACK vs. a "pop". Feels like a gun again!!!
Took a few 5-shot groups with other pellets too, posted below.
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GREAT!
Perseverance has paid off.
Congrats on a job well done.
Now, don't be a stranger and keep us posted.
;-)
HM
PS.- I am glad I was wrong. LOL!
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Thanks Hector! Without your help I never would have been able to get this far.
One interesting takeaway is the size of the transfer port on this gun. At 4.65mm (and breech seal TP at 5.5mm), requires care with pellet seating, at risk of the pellet falling backwards into the compression chamber. Like the smushed pellet I found on initial disassembly.
Another takeaway is that the spring tension should be pretty strong, as the stroke is on the short end and the piston diameter isn’t large either. The original springs, amd the new ARH springs, were both very easy to handle with my homemade gun vise - too easy as it turned out. Was immediately noticeable how much more force was required to compress the WCG springs. I believe this was the #1 factor in fixing the issue.
Last takeaway was the breech seal and piston seal. I think the less-thick ARH version could possibly work but needs about 1mm of shim behind it. The red ARH plastic is also quite a bit softer than the WCG green material. Getting those green WCG parts to seat was a real chore.
I’m less sure about the ARH piston seal. It juts out well beyond the end of the piston and shortens an already short stroke. It would probably work ok but I would expect a drop in velocity.
Ironically, the piston ring was probably A-OK as is. Live and learn!
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I am glad you are happy!
Just not to leave any stone unturned, I would test the ARH springs with the WCG bumper.
IMHE, match guns need precious little "force" to generate energy.
And, yes 2 mm's stroke difference in ANY piston airgun will mean 1 to 2 ft-lbs difference in output.
Keep well and shoot straight!
HM