Simple Akela hammer spring cutting (clipping) instructions

[kerplunk]

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.


Step 5 is here: 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

[Rat Sniper (AKA: PaulT58)]

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. 

[johnbrown]

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.

[kerplunk]

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!

[Ribbonstone]

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.

----------
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.

[FuzzyGrub]

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. 

[Rat Sniper (AKA: PaulT58)]

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.

[johnbrown]

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.

[kerplunk]

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

[johnbrown]

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.

[kerplunk]

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.

[FuzzyGrub]

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. 

[Rat Sniper (AKA: PaulT58)]

Yep, they really topped off my Cayden!  This is how I received it from Crosman!  It definitely holds air!  LOL!

[johnbrown]

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.

[Rat Sniper (AKA: PaulT58)]

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.

[FuzzyGrub]

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.   

[Rat Sniper (AKA: PaulT58)]

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!   

[FuzzyGrub]

Yes, the Troy!  Mr Hammer. 

[Rat Sniper (AKA: PaulT58)]

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! 

[FuzzyGrub]

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.