Anschutz 380 - specs and disassembly

[jimk1963]

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.

[chuckinohio]

  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.

[chuckinohio]

 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

[HectorMedina]

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

[jimk1963]

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...

[chuckinohio]

  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.

[Yogi]

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

[jimk1963]

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.

[jimk1963]

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?

[HectorMedina]

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

[jimk1963]

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.

[chuckinohio]

  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.

[jimk1963]

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.

[HectorMedina]

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

[jimk1963]

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.

[HectorMedina]

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

[jimk1963]

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

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: 

[jimk1963]

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?

[HectorMedina]

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

[jimk1963]

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.