I've been thinking about this since I bought the power plenum in July, and finally decided to try and "power tune" the .22 Cricket mini Carbine to shoot the JSB .22 RD Monsters at a good speed, preferably at 875 FPS if at all possible, while still retaining a minimum of 35 shots per fill to 250 bar. The gun is currently a 30 FPE gun, 55 shots on reg. per 250 bar fill, and I'd be going up to 42 to 43 FPE. What I want to get is "standard" .25 "JSB King" performance from a small, light, super accurate and easy to shoot gun like the Cricket mini. I had considered the Wildcat Compact in .25, but the FX really only shoots one pellet well and with the CZ hammer forged barrel, the Cricket will leave the door open to other "heavy" .22 caliber pellets. So, the overall plan is this:
1. Add additional "power plenum", purchased from Ernest a while ago on eBay. Not sure if I'll drill and tap for a reg. pressure gage yet.
2. Replace valve spring with longer, lighter spring and adjust as per Ernest's video.
3. Replace hammer spring with stronger spring. I have three different Cricket sized hammer springs that I can experiment with.
4. Replace the plastic HST adjuster with a metal one.
5. Port and polish the air inlet to the valve (small holes will be polished and holes chamfered, not enlarged much).
6. Enlarge valve port by enlarging it in an "oval" shape by 0.5mm on each side, and chamfer port edges.
7. Enlarge barrel port in the same manner as the valve port.
8. Add Huma reg. to replace the Cricket reg. I don't think the Huma is any better than the Cricket, but it is much easier to adjust, especially without a reg. tester. If I had a reg. tester I would use the Cricket reg. after polishing the Belleville washers as per Ernest's video. Without a reg. tester it would involve too much in and out to get it just right. With the Huma I can at least adjust per the label and be "close", since in my experience with other Huma regs. the label in bar has always been pretty close to reg. set pressure.
Finally, once assembled, and reg. set to 145 to 150 bar to start, tune the gun using reg. pressure and HST as discussed in numerous posts on this forum. From what I gather from Jimmy's .22 pup power tuned by Derek, the CZ barrel "should" be accurate with the RD Monsters. Yes, its 2 inches shorter than the pup, but other than that the same. Since Derek got around 885 FPS with his tune, I feel that I can get around 860, but my goal is 875, and still get a good number of shots (35) from a 250 bar fill.
We'll see how it goes. I have most of the parts now, but still need the Huma to start the tune. More to follow...
Mike