This is really old news, but since I just got around to doing it... I re-ordered some hammer springs for the Akela since I seem to have lost my earlier spares, and interestingly they came in at 77mm long - much shorter than the stock 90 or so mm one. Per @EPG's old posts I cut 1-1/2 coils off, then tried to finish the end with heat & a dowel guide, ending at about 2.59" (65.7mm). I played with turning in the hammer spring a bit, and ended with about 1.5 turns in. I tried H&N Baracuda Match 10.65, FX 10.3, and CPHP 7.9. They all looked great at 25 yards, so I went out to about 48 yards, where the FX clearly came out on top; my best that day was about an inch 10 shot group. It's nice to know the cheap CPHP do well at the close-in ranges. This day ended before I tested the CPUM due to a leaky "power adjuster" o-ring. Conveniently a spare Kozak fill probe ring was a close enough fit to keep me from having to order more rings just yet.
Last weekend I wanted to test the shot count with the modified spring, so I ran CPUM 10.5gr over the chronograph (no accuracy testing). I ran nine, 14-round mags from 3000psi down to 1400. Before shortening the spring, 5 test shots of CPUM averaged 1035fps, 25 ft-pounds. This time I got 855fps average over the 126 shots, at 17ft-pounds. Trimming down to about a 40 fps spread (actually 42fps) I got 90 shots, 867fps average at 17.5ft-pounds. I think I'll try Airgun Revisions spring kit sometime, just to compare.
The entire run (blue & green cells) are reflected in the upper velocity chart, while the 42fps sub-group (green cells) are in the lower velocity chart. I *think* my formulas are all good.
I'm really pleased how nice this gun is - makes me appreciate .177 a little more. And, the gun was only $330 during a sale in 2022. The stock is gorgeous, especially after 4 rubbed-in coats of Howard Feed-N-Wax. You'll note in the photo below I had just put the stock back on the gun, and forgot to fully screw the butt pad on. It's got a Buck Rail moderator, and Immersive Optics 5x30 scope.
Last weekend I wanted to test the shot count with the modified spring, so I ran CPUM 10.5gr over the chronograph (no accuracy testing). I ran nine, 14-round mags from 3000psi down to 1400. Before shortening the spring, 5 test shots of CPUM averaged 1035fps, 25 ft-pounds. This time I got 855fps average over the 126 shots, at 17ft-pounds. Trimming down to about a 40 fps spread (actually 42fps) I got 90 shots, 867fps average at 17.5ft-pounds. I think I'll try Airgun Revisions spring kit sometime, just to compare.
The entire run (blue & green cells) are reflected in the upper velocity chart, while the 42fps sub-group (green cells) are in the lower velocity chart. I *think* my formulas are all good.
I'm really pleased how nice this gun is - makes me appreciate .177 a little more. And, the gun was only $330 during a sale in 2022. The stock is gorgeous, especially after 4 rubbed-in coats of Howard Feed-N-Wax. You'll note in the photo below I had just put the stock back on the gun, and forgot to fully screw the butt pad on. It's got a Buck Rail moderator, and Immersive Optics 5x30 scope.
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