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.
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.
The above pic shows how I document what I did to the gun, the stock covers this portion of the gun.
The above pic shows the finished product in a skeleton stock.
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.
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