New 2260 on HPA

[poil27]

nice , seams to work great

[rsterne]

I spent the day fitting a .25 cal 24" long TJ's Barrel Liner that I got from Stan at AeroTec.... I machined the transfer port in the same location as a Crosman barrel and made it fit a poly port, so it's interchangeable with the .22 cal barrel.... it's even the same OD.... I had to make a new bolt as well, and the first few shots across the Chrony showed that it shoots 25.3 gr. JSB Kings at nearly the same velocity as the 18.1 gr. Heavies shot in .22 cal.... Here is how the velocity and efficiency worked out at various hammer spring settings....



I didn't bother testing lower settings, as the whole point of a .25 cal (to me) is power.... At maximum preload, I only got 18 shots, the gun was using over 80 psi per shot, and MAN was it loud.... but it was shooting over 50 FPE with the JSB Kings.... At 1 turn out on the preload, I only lost 8 fps, I picked up 3 shots, and the gun was noticeably quieter.... Another turn out, the shot count increased to 28, and I was still getting 47.5 FPE.... At 3 turns out, the velocity was averging 886 fps (44 FPE), it was probably about half as loud as at maximum power (or less) and I got 40 shots from 3000 psi down to 1300 (300 psi below the setpoint).... The fastest shots (by just a few fps) were two-thirds of the way through the shot string.... and the efficiency at that power level was 1.16 FPE/CI.... This is about the same power I have my .25 cal Disco set up for, but I only get 11 shots....

I tried the heavier pellets at the maximum setting, with these results....

25.3 gr. JSB Kings - 945 fps - 50.2 FPE
30.9 gr. H&N Baracuda - 892 fps - 54.6 FPE
35.3 gr. EunJin Domes - 853 fps - 57.0 FPE
42.4 gr. EunJin Points - 794 fps - 59.4 FPE

So if I don't care about shot count and noise, this gun shoots 50-60 FPE in the .25 cal version.... Knowing that, I detuned it to 2.5 turns out on the hammer spring preload, which gave me an average velocity of 907 fps with the JSB Kings.... and another beautiful shot string....



The gun is using 50 psi per shot to produce 46.2 FPE, and I got 33 shots between 904 and 912 fps (a 1% range).... Even though the setpoint of the regulator is about 1600 psi, I can shoot down to 1300 before the velocity drops below 900 fps.... I can't wait until spring when I get a chance to find out what the accuracy is like....

Bob