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Fine tuning the .22 Cricket Standard Bullpup with Georgia Airguns Powertune..

May 29 2017 at 11:08 AM
Charlie Frear, Georgia Airguns  (Login GeorgiaAirGuns)
YF12

I decided to take a day to just experiment and tinker, it is what I like to do best with these high end PCP's.
I pulled out a .22 Cricket Standard that I already powertuned. I wanted to go into it a little further and see if I could make it perform even better.
The primary goals of this mission was to get it to shoot the 18 grain JSB and Air Arms pellet as fast, accurately and as many as possible without stressing the internals of the gun.
I first took the barrel and airtube out of the receiver to compare the size of the transfer port in all three components. I found they all three had slightly different diameter openings.
After I found a short bolt that I could get to barely drop in the transfer port on the receiver to get a very close actual size of the transfer port, I used that bolt as a reference to size the transfer port leaving the airtube and the port entering the barrel. Sorry I don't have any pictures on this, but after some milling, drilling and dremeling I was able to make all three transfer ports very close to the same size.
Next was to take some of my normal additional steps to make sure I had exact alignment on all three ports.

[linked image]
Pictured above are the parts to this powertune that were changed or altered. The LDC was extended to stick out past the now longer airtube, the airtube extension (pictured) adds about 1 3/4 inches to the overall length of the airtube, so I had Neil Clague add about two inches to the LDC.
You can also see that I changed the reg setting to 117 BAR form the factory 105 BAR along with using a metal hammerspring adjuster to adjust the factory hammerspring.
In the end these changes did very little to add any stress to the internals of the gun.

[linked image]
The above pic shows how I document what I did to the gun, the stock covers this portion of the gun.

[linked image]
The above pic shows the finished product in a skeleton stock.

[linked image]
Above, shows the gun in full dress weighing in at 8.4 pounds, the Sightron S-TAC 4x20x50 with its great glass is one of the lighter side focus scopes out there at 23.5 ounces.

[linked image]

Finally the part that counts, you can see some impressive groups with the 18 grain Air Arms Diabolo Field Heavy. Shooting at about 935 FPS, I was able to get right at 60 shots at this power setting.
You can also see the 16 grain pellets did okay at about 965 FPS.
In the end there was not as much power gained as when I do the same Powertune to .25 Cricket Bullpup.
I am pleased with the accuracy and the shot count resulting from this powertune. I really like working on these Crickets, they are really easy to fine tune.

Thanks for reading.

Charlie Frear, Georgia Airguns
georgiaairguns.net
706-884-6707


    
This message has been edited by GeorgiaAirGuns on May 29, 2017 11:14 AM


 
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AuthorReply
Ron Robinson
(Login compressive)
YC

Good stuff, Charlie!

May 29 2017, 2:12 PM 

But we've come to expect nothing less from you, Bud. You came very close to reading my mind on this one, though.

As you know, my primary interest in long-range airgunning centers around the Bench-Rest Silhouette matches we shoot in my neck of the woods. From what I can tell, a CF-tuned .25 Cricket seems to be about the best choice, though I'm experimenting with .22 and .25 Korean magnums (Careers and Sumatras), and holding my own.

That said, it seems to me that the new 34 grain .22 JSB's around 800-900 FPS might be even better (ballistically) than the 34 grain .25's at similar speeds, given a rifle with enough guts to get there and stabilize them with TACK-DRIVING accuracy. I'd be VERY curious about how accurately the .22 Cricket in your post would shoot the 34 grain JSB's. Hoping to pique your curiosity about that, as well.

FWIW, I just tuned a .22 Sumatra DOWN to shoot the 34 grain JSB's about 800 FPS. I figured if there was ANY air rifle that might shoot super-heavy pellets well it would be the Korean magnums designed for that very purpose. Nevertheless, the 34's weren't as accurate as I'd hoped in the Sumatra; so wonder how well the magnumized .22 Cricket would shoot 'em.

Thanks for the awesome post, Charlie. Keep up the good work.

 
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Charlie Frear, Georgia Airguns..
(Login GeorgiaAirGuns)
YF12

Will give it a try..

May 29 2017, 6:14 PM 

Ron, I thank you for your appreciation about the time and effort I have put into this gun and thread.
I will get hold of some 34 grainers and see what kind of power I can get with the very heavy JSB. Keep in mind with a heavier pellet it is in the barrel longer, which means I can make a few more minor changes to get a little more pressure behind that 34 grainer.
I will keep you posted.

Thanks

Charlie Frear, Georgia Airguns

 
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CheckUrSix
(Login CheckUrSix)
YF12

I too, would like to see data on the 34 grn JSB n' .22 cal, My

May 29 2017, 4:56 PM 

Hummingbird is shooting jsb 18's GREAT @ 945 fps gett'n approx the 965 fps w/16's. What would you expect to see FPS in the 34 grns?
Thanks


    
This message has been edited by CheckUrSix on May 29, 2017 4:56 PM


 
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JD
(Login JamesDingle777)

780fps if your lucky N/T

May 29 2017, 9:27 PM 


 
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CheckUrSix
(Login CheckUrSix)
YF12

Ouch....Far too Loopy for me! n/t

May 30 2017, 4:07 AM 


 
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