I did some more tuning with my .22 MROD and I shot a pretty good string with the Crosman premier 14.3 The high fpe shot of the string yielded 31.12 fpe @ 990 fps
SP 3100 psi
Hammer spring preload: 3 turns in (halfway) from longest travel.
Hammer stroke : MAX (counter clockwise) Note: any adjustment in with this high of a fill pressure caused the fps to drop significantly...
Transfer port metering screw 3/4 turn in from "wide open"
I decided to give some heavier pellets 21.10 gr Kodiaks a try with the same start pressure, same settings. If I decide to tune this rifle to shoot the heavier kodiaks or cudas...I think a turn or two on the hammer spring preload will get me into the curve much quicker...and I will try this next time I test....but overlooking the slow climb, the heart of the curve was very nice indeed!
shot #23 yielded 36.044 fpe @ 877 fps
end pressure 2100 psi
I tried a fill pressure of 100 to 150 psi less and it gave me an average velocity of 10fps slower than the one above, but it dropped off quickly after shot 26. I'd really like to stick with a 3100 psi fill for the purpose of this tune, so I am thinking some more hammer preload is the answer perhaps with a little transfer port metering screw adjustment.
I am curious to check out my accuracy with this new setting as the shorter hammer spring travel should yield less "hammer bounce", ie. recoil.
DAY THREE: ACCURACY TESTING.
The Kodiaks were very frustrating! I would shoot two 1/4" 5 shots group back to back @ 20 yards, and the third group would look like "buck shot", ARRRRRGGGGHHHHHHH! JSB's are even worse!!! For now I am giving up on the heavier pellets. I left the tune as it is above with the 14.3 crony string and I managed some very impressive groups @ 20 yards (I will, however, need to test the 14.3 premiers at 50 yards as some say they will destabilize at the high speeds I am shooting them...I will test and report my findings when I have time...) Here are my groups:
I filled to slightly less fill pressure than the crony string above 2900 to 2950...psi and I shot the first 10 pellets at random targets to set zero of new scope, then 2--10 shot groups, refilled again to the same pressure and shot another 3 ten shot groups all from 20 yards.
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