GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: kerplunk on December 15, 2021, 11:33:54 AM
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This is an extremely easy process whose individual steps have already been explained elsewhere, so rather than reinvent the wheel with a new document or video I thought I would give a simple explanation and post links here:
1. Decock gun. Degassing is also the safe and smart thing to do, but not absolutely necessary.
2. Remove action from stock.
3. Punch out rear pin.
4. Remove hammer spring adjuster and spring.
5. Clip a coil from the spring and reform it using the instructions below.
6. Put everything back together by reversing the steps. It annoys me greatly when people just say "reverse the steps" and there end up being tricky bits they didn't warn about, but reassembly is very straightforward in this case.
Steps 1-4 are in this video. Watch the first minute and then skip ahead to 12:30. You don't have to do any of the stuff in between, assuming you have the US version without the anti-tamper device.
https://youtu.be/EwWQi_R5-n8 (https://youtu.be/EwWQi_R5-n8)
Step 5 is here: https://www.airgunnation.com/topic/cutting-an-airgun-spring/
(https://www.airgunnation.com/topic/cutting-an-airgun-spring/)
If you'd like to de-tune your gun without doing irreparable damage to the factory spring I highly recommend checking out this great thread from FuzzyGrub: https://www.gatewaytoairguns.org/GTA/index.php?topic=194057.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=194057.0)
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I just did this. My stock spring was 3.43" long. I ordered a spare from Crosman and cut it down to 3". It may need to be shorted a bit more, but I'm waiting for the regulator to arrive before I do anything else with the hammer springs. Here the the before and after results of the 2 pellets that are grouping the best in my Akela:
Before:
Pellet: AA
Grains: 10.30
Shot 1: 1053.00
Shot 2: 1051.00
Shot 3: 1055.00
Shot 4: 1044.00
Shot 5: 1046.00
Avg FPS: 1,049.80
Avg FPE: 25.21
Spread: 11.00
Pellet: CPUD
Grains: 10.50
Shot 1: 1000.00
Shot 2: 990.00
Shot 3: 990.00
Shot 4: 984.00
Shot 5: 981.00
Avg FPS: 989.00
Avg FPE: 22.81
Spread: 19.00
After:
Pellet: AA
Grains: 10.30
Shot 1:997.00
Shot 2: 1000.00
Shot 3:997.00
Shot 4: 1000.00
Shot 5: 997.00
Avg FPS: 998.20
Avg FPE: 22.79
Spread: 3.00
Pellet: CPUD
Grains: 10.50
Shot 1:974.00
Shot 2: 974.00
Shot 3: 974.00
Shot 4: 972.00
Shot 5: 972.00
Avg FPS: 973.20
Avg FPE: 22.09
Spread: 2.00
Not only are they shooting slower, the spread has been reduced significantly! It now has a much flatter shot string.
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I used a rotary tool (Dremmel, Wen ,etc) and a cutting wheel to clip my .22 Akela hammer spring about 1 coil at a time.
Then used the same tool and a grinding stone to grind/flatten the cut end.
Right now I am at about 2.5 coils cut, zero preload and the velocity bell curve starts around 3100-3200 PSI, peak around 2600-2800 PSI, and ends around 2000-2200 PSI with CPHP .22.
Over the above pressure range above the velocity goes from around 870 FPS to around 900 FPS.
Initially with the uncut spring the bell curve was moved to a much higher PSI (probabnly closer to 400 PSI) and I did not dare fill more than 3400 PSI.
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My Akela came shooting HOT at almost 970 FPS with H&N Baracuda 18.13gr pellets for almost 38 FPE, but was down to 880 FPS after 24 shots with a steadily declining string. Cutting one coil got me to ~940 FPS/35FPE but declining steadily after 12 shots. Cutting a second coil got me to a very consistent ~900 FPS/33 FPE for 24 shots and a gentle decline after that. I'm leaving it like this for now, even though the shot count is a little low I'm happy with it since it's still shooting pretty hot and the first 24 shots only have ~1% ES.
I'll eventually get another spring or two and try to tune it for ~50 shots at 30 FPE, as that seems to be the sweet spot from what others have posted, but for now I'm just going to enjoy shooting it for awhile!
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Maybe they’ll get the idea...not the first PCP where the makers changed the spring used.
An adjuster to maxes out (minimum or maximum) on the way to where you want to go is basically non-adjustable. This sounds like one of those, backed out to the adjuster limits, for minimum tension, it still falls off a cliff.
Still are some PCP’s with no built in spring adjustment. Change springs, cutting springs, shimming springs….going in little steps with a tests in between.
Back to old-school spring cutting, but in this case, cut so the adjuster actually served a use. Wouldn’t want to get it “just right” with the adjuster set at min or max.
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Breaking the “golden rule”. Never do any “work” on a charged PCP.
Suspect breaking that rule is part of the plan for spring cutting. After all (we think), how is it really any more dangerous than just taking off the stock? All the valve fixation is still in place either way.
Because we plan of fiddling around with one of the vital parts that make a PCP go “bang” ….on a pressurized PCP that can go bang.
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What is interesting is, don't recall discussion on declining strings on the Cayden. All the key parts are the same, except the barrels are 2" longer.
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What is interesting is, don't recall discussion on declining strings on the Cayden. All the key parts are the same, except the barrels are 2" longer.
This is true. My Cayden right out of the box had a shot string that could rival that of a regulated rifle! The Akela, on the other hand was like launching off a ski slope! That that seems to be the case with both the .22 and .177 versions.
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My Akela came shooting HOT at almost 970 FPS with H&N Baracuda 18.13gr pellets for almost 38 FPE, but was down to 880 FPS after 24 shots with a steadily declining string. Cutting one coil got me to ~940 FPS/35FPE but declining steadily after 12 shots. Cutting a second coil got me to a very consistent ~900 FPS/33 FPE for 24 shots and a gentle decline after that. I'm leaving it like this for now, even though the shot count is a little low I'm happy with it since it's still shooting pretty hot and the first 24 shots only have ~1% ES.
I'll eventually get another spring or two and try to tune it for ~50 shots at 30 FPE, as that seems to be the sweet spot from what others have posted, but for now I'm just going to enjoy shooting it for awhile!
After cutting 2 coils you still do not have the entire shot string bell curve .
The ascending part of the bell curve is missing.
I cut 2.5 coils from my .22 Akela and with 0 preload (max power) I have the ascending shot string starting around 3200-3300 psi with a flat velocity zone from 2900-3000 psi down to about 2200-2300 psi.
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My Akela came shooting HOT at almost 970 FPS with H&N Baracuda 18.13gr pellets for almost 38 FPE, but was down to 880 FPS after 24 shots with a steadily declining string. Cutting one coil got me to ~940 FPS/35FPE but declining steadily after 12 shots. Cutting a second coil got me to a very consistent ~900 FPS/33 FPE for 24 shots and a gentle decline after that. I'm leaving it like this for now, even though the shot count is a little low I'm happy with it since it's still shooting pretty hot and the first 24 shots only have ~1% ES.
I'll eventually get another spring or two and try to tune it for ~50 shots at 30 FPE, as that seems to be the sweet spot from what others have posted, but for now I'm just going to enjoy shooting it for awhile!
After cutting 2 coils you still do not have the entire shot string bell curve .
The ascending part of the bell curve is missing.
I cut 2.5 coils from my .22 Akela and with 0 preload (max power) I have the ascending shot string starting around 3200-3300 psi with a flat velocity zone from 2900-3000 psi down to about 2200-2300 psi.
Thanks Captain Obvious. As I mentioned twice in the post that you quoted by clearly didn't read, I'm well aware that I could get more shots with additional work. I would either need to cut more coils or fill to a higher pressure to get the entire bell curve, and I'm not interested in doing either of those at the moment. Cutting another coil would result in lower power, and going over max fill pressure may blow the burst disc, and just isn't good practice in general. It sounds like you're shooting ~25.7 FPE on your nice bell curve, but for now I'm happier with 24 flat shots at 32.9 FPE. You know, like I said already in the post you quoted :)
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My Akela came shooting HOT at almost 970 FPS with H&N Baracuda 18.13gr pellets for almost 38 FPE, but was down to 880 FPS after 24 shots with a steadily declining string. Cutting one coil got me to ~940 FPS/35FPE but declining steadily after 12 shots. Cutting a second coil got me to a very consistent ~900 FPS/33 FPE for 24 shots and a gentle decline after that. I'm leaving it like this for now, even though the shot count is a little low I'm happy with it since it's still shooting pretty hot and the first 24 shots only have ~1% ES.
I'll eventually get another spring or two and try to tune it for ~50 shots at 30 FPE, as that seems to be the sweet spot from what others have posted, but for now I'm just going to enjoy shooting it for awhile!
After cutting 2 coils you still do not have the entire shot string bell curve .
The ascending part of the bell curve is missing.
I cut 2.5 coils from my .22 Akela and with 0 preload (max power) I have the ascending shot string starting around 3200-3300 psi with a flat velocity zone from 2900-3000 psi down to about 2200-2300 psi.
Thanks Captain Obvious. As I mentioned twice in the post that you quoted by clearly didn't read, I'm well aware that I could get more shots with additional work. I would either need to cut more coils or fill to a higher pressure to get the entire bell curve, and I'm not interested in doing either of those at the moment. Cutting another coil would result in lower power, and going over max fill pressure may blow the burst disc, and just isn't good practice in general. It sounds like you're shooting ~25.7 FPE on your nice bell curve, but for now I'm happier with 24 flat shots at 32.9 FPE. You know, like I said already in the post you quoted :)
I apologize if my post somehow offended you.
I read all the posts on this thread again. For the past 2 weeks I have also spent many hours researching everything related to the Benjamin Akela/Cayden/Kratos.
Thank you for mentioning the burst disk, which seems to be part CR-058.
I have many times filled my Akela to 3300-3400 psi and the disk did not burst.
Filling to 3300-3400 PSI gives me 5-6 magazines with a 30-35fps spread.
Filling to 3000 psi would give me only 3-4 magazines, which is bad in my view from a 280cc tank.
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My Akela came shooting HOT at almost 970 FPS with H&N Baracuda 18.13gr pellets for almost 38 FPE, but was down to 880 FPS after 24 shots with a steadily declining string. Cutting one coil got me to ~940 FPS/35FPE but declining steadily after 12 shots. Cutting a second coil got me to a very consistent ~900 FPS/33 FPE for 24 shots and a gentle decline after that. I'm leaving it like this for now, even though the shot count is a little low I'm happy with it since it's still shooting pretty hot and the first 24 shots only have ~1% ES.
I'll eventually get another spring or two and try to tune it for ~50 shots at 30 FPE, as that seems to be the sweet spot from what others have posted, but for now I'm just going to enjoy shooting it for awhile!
After cutting 2 coils you still do not have the entire shot string bell curve .
The ascending part of the bell curve is missing.
I cut 2.5 coils from my .22 Akela and with 0 preload (max power) I have the ascending shot string starting around 3200-3300 psi with a flat velocity zone from 2900-3000 psi down to about 2200-2300 psi.
Thanks Captain Obvious. As I mentioned twice in the post that you quoted by clearly didn't read, I'm well aware that I could get more shots with additional work. I would either need to cut more coils or fill to a higher pressure to get the entire bell curve, and I'm not interested in doing either of those at the moment. Cutting another coil would result in lower power, and going over max fill pressure may blow the burst disc, and just isn't good practice in general. It sounds like you're shooting ~25.7 FPE on your nice bell curve, but for now I'm happier with 24 flat shots at 32.9 FPE. You know, like I said already in the post you quoted :)
I apologize if my post somehow offended you.
I read all the posts on this thread again. For the past 2 weeks I have also spent many hours researching everything related to the Benjamin Akela/Cayden/Kratos.
Thank you for mentioning the burst disk, which seems to be part CR-058.
I have many times filled my Akela to 3300-3400 psi and the disk did not burst.
Filling to 3300-3400 PSI gives me 5-6 magazines with a 30-35fps spread.
Filling to 3000 psi would give me only 3-4 magazines, which is bad in my view from a 280cc tank.
I apologize for being a little nasty. One of my biggest pet peeves is when people respond to a post without having read it, and considering I mentioned twice in my post that I was well aware I could achieve more shots, that seemed to be the case here.
Thanks for sharing your experience. Not everyone has the same goals in tuning. While you may be happy with 5-6 mags at ~25.5 FPE and 3-4% ES by overfilling, I'm pretty happy with 2 mags at ~33 FPE with 1% ES by filling to manufacturer's recommendation.
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FWIW: I think it might have been Paul, that reported getting his Cayden with 3800psi fill. It wasn’t valve locked at that psi either. Burst disk is probably 4K or higher.
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Yep, they really topped off my Cayden! This is how I received it from Crosman! It definitely holds air! LOL!
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If I could not overfill to get 5-6 magazines of shots I would just return the Akela since in 2021 I cannot put up with unregulated PCPs with poor shot strings.
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The Lane regulator I ordered arrived today, but I’m at a dead stand still on the install! Apparently the air cylinder is glued to the block! I have tried heat and PB Blaster penetrating oil and can not get it to budge! Not sure what to try next, I don’t want to mar the block or the air cylinder, so not sure where to go from here.
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The Lane regulator I ordered arrived today, but I’m at a dead stand still on the install! Apparently the air cylinder is glued to the block! I have tried heat and PB Blaster penetrating oil and can not get it to budge! Not sure what to try next, I don’t want to mar the block or the air cylinder, so not sure where to go from here.
I saw that on the video, but was thinking/hoping it was a UK version thing.
I'd IM Troy for ideas. I think he had all three Kralman's apart to see if his valve fit.
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John, you referring to Troy Hammer? or another Troy? I'll do a search of his posts to see if he posted any hints before I bug him! Thanks...
I was hoping it was just a UK thing also, like the anti-tamper grub screw on the hammer spring adjuster that we don't have. But, no luck, it's locked up tighter than a... Well, you know what I mean! ;D
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Yes, the Troy! Mr Hammer. :)
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Thanks! I searched his posts but didn’t see anything specifically addressing the removal of the air cylinder from the block, so I sent him a PM, just waiting now and hoping he may have a suggestion that will work.
I’m at my wits end with it now, even got a hotter heat gun in the hopes that would loosen any glue or whatever gunk they have binding it together, so far no luck at all with heat!
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Yea, surprised heat didn't do the trick.
You have me wondering if it is just anti-tampering, or actually needed for integrity. Troy probably knows.
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Well, I went at it from a different angle... Literally! Instead of removing the block from the cylinder, I removed the other end with the Foster Fitting. It came right off! So, I inserted the regulator from that end. I have no idea if it will work or not since I wasn't able to vent the tube like it showed in the video. Then again, the instructions said nothing about cutting a vent line in the threads like the video showed, so who knows. I put it all back together (and I mean everything to include the scope), went to fill it and it was leaking air! So, tore it all down again, pulled the valve from the block (I had removed it so the o-rings wouldn't be damaged when I was heating it), and found one of the o-ring had broke. Scavenged around till I found one that fit and put it back together. Just the cylinder, block and valve this time. It still leaked and was coming from the burst disk. So, had to find an allen wrench that fit because that one's an odd size. Turns out it was just loose. So, I snugged it down tight and gave it a 2000 psi fill. It's sitting at that pressure now to see if it holds air. If it holds air over night, I'll put it back together and give it a try tomorrow to see what happens. One of the small screws that hold the side plate on the trigger stripped out the hex head, so now that's stuck. I have to remove the nut on the trigger linkage to remove that part. The nut was tightened all the way onto the threaded rod, so I'll just snug it back down as far as it will go when I reassemble it. This turned into much more of a project than I anticipated! I've installed a lot of regulators in Marauders and Hatsan AT-44's, and none of those were near as frustrating as this one!
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My $200 Nova Liberty .22 shoots much better than my $400 Akela .22, more accurate (with cheap pellets), much lighter, very long shot strings.
I will still keep the Akela since it would be too much of a headache to return it anyways :)
The Benjamin Akela/Cayden/Kratos have on their side not great performance but the great looking stock and the Crosman warranty and part availability.
And that is the best I can say about the Benjamin Craftsman air rifles.
The warranty may be meaningless if you decide to tune it because you are not happy with the 24 good shots out of the box.
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Paul,
I'm hoping it held overnight.
Here is what I have put together on the O-rings, so far. The sizes came from crosman notes, in the earlier schematics. Some do not seem to be correct (yellow) and have only checked the ones I purchased.
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Paul,
I'm hoping it held overnight.
Here is what I have put together on the O-rings, so far. The sizes came from crosman notes, in the earlier schematics. Some do not seem to be correct (yellow) and have only checked the ones I purchased.
Thank you John! Looks like I'll be ordering some o-rings! It's sitting at 1500 psi this morning. I'll have to air it up to 3000 psi and do some dunking to see if I can find where it's leaking.
I'm going to have to order a couple new screws for the trigger plate as well and hope I can get the stuck one out of there. I don't recall really tightening either one more than just snug, so I'm not sure how it got so tight it rounded out the hex end. That's really frustrating, not sure why they can't use hardened screws one these thing!
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Yep, they really topped off my Cayden! This is how I received it from Crosman! It definitely holds air! LOL!
Your gauge face looks to me like it is bent on it's shaft and the center of the face is not at the base of the pointer.
If straightened the dial might point to 3000.
My akela came with the gauge bent and the dial did not rotate around the face correctly.
Crosman sent me a new gauge.
After I got the new gauge I did straighten the original and did not break it.
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My gauge is straight, I think it’s just the angle of the photo. That photo was taken right after I took it out of the box. I have had the stock off and the gauge does not appear to be bent at all. I would like to get an extender for it though, it would be a lot easier to read if it was closer to flush with the bottom of the stock.
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I filled it to 3000 psi and did a leak test. There was still a very slight leak coming from the burst disk, so I tighten that a bit more and am waiting to see if it holds air.
I’m still not 100% convinced the regulator is working. The instructions said no breath hole required, but, the o-ring on the block is still there and my gauge is reading 3000 psi, not the regulated pressure of 2000 psi, so not sure if this was a waste of time or not at this point.
If it holds air for the next hour or two, I’ll reassemble it and do a shot string over the Chrony to see how it looks.
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Well, here's the shot string, started out with a 3000 psi fill, ended with around 1800 psi left in the cylinder. A total of 56 shots shooting CPUD 10.5 grain pellets:
Shot count: 56
Low: 895
Hi: 972
Avg: 948
Spread: 77
STD Dev: 22.4
967
970
967
960
967
965
967
960
965
967
967
965
963
960
972
965
970
960
967
967
960
965
965
958
965
956
960
960
960
960
958
956
946
951
946
935
949
949
944
942
942
935
928
930
932
926
921
919
916
909
909
905
905
898
895
895
Here's the graph, the shot string starts on the right side and ends on the left.
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Well, here's the shot string, started out with a 3000 psi fill, ended with around 1800 psi left in the cylinder. A total of 56 shots shooting CPUD 10.5 grain pellets:
Shot count: 56
Low: 895
Hi: 972
Avg: 948
Spread: 77
STD Dev: 22.4
967
970
967
960
967
965
967
960
965
967
967
965
963
960
972
965
970
960
967
967
960
965
965
958
965
956
960
960
960
960
958
956
946
951
946
935
949
949
944
942
942
935
928
930
932
926
921
919
916
909
909
905
905
898
895
895
Here's the graph, the shot string starts on the right side and ends on the left.
The regulator pressure may be too high since you only get 40-50 good shots from a 280cc tank.