Hey whats a good tune for jsb 25.39 or fx 25.39 pellets.. please include hammer spring and reg pressure and fps. I was thinking low 880 and high 915 fps
Tuning fx impact mk2 .25
- Thread starter addison
- Start date
Each rifle is different. You will probably have to experiment with different tunes to get to where you desire. That is part of the fun and the challenge -- for me.
The speeds you cite are in the ballpark. If I recall correctly, Ted Bier has even recommended a velocity of ~850fps for the diabolo pellets. Check out some of his videos on tuning the Impact.
The speeds you cite are in the ballpark. If I recall correctly, Ted Bier has even recommended a velocity of ~850fps for the diabolo pellets. Check out some of his videos on tuning the Impact.
Upvote 0
I have a .25 Impact with Power Plenum, Huma Dual Transfer port, Superior liner, new FX pin probe, Regulator set at 85 Bar, shooting JSB 25.39 at 930 - 935 FPS and its extremely accurate at 100 Yards. Getting 100+ shots on a 240 Bar Fill. I personally find the higher speed more accurate. I put thousands of shots thru it at 880 to 910 PFS, but I have now discovered its more accurate at the higher speeds with all the upgrades. I also have installed the carbon fiber sleeve on my superior barrel (no more o rings, thank you Ernest). I think that also has resulted in better groups and less POI shift. Of course every gun is different, but one thing for sure, the upgrades have certainly improved everything on my impact and made it more air efficient as well. Have fun, good luck.
Upvote 0
That's a good velocity range...Even a little higher if needed, but shot count will be a trade-off. It will also depend on the harmonics/best groups. The Superior liner will shoot those Kings at many different velocities very well. I would set the reg at 100 PSI for a good starting range.
Upvote 0
Depends on your current gun setup. Is it the Impact X without the power plenum? or Is it with the PP? When I shot 25.39 g JSB's through my Impact X without PP, it was harmonically tuned like this: Hammer approx 18mm. Valve stop at 3rd mark. Reg press at 125 to 130. At this setting I was getting shots past the 930 fps mark at Max. I used to have it dialed down to 3 or 4 which had the fps as you indicated 870 to 920 fps. Now, with the JSB's MK II's 33.9 g, I was getting around 915 fps at Max, and it shot best at the 3 or 4 mark on the power wheel giving fps between 840 and 880. These were for the same settings above.
Now with the PP on my gun and re tuning everything: at these settings: Reg 115-120, Hammer approx 17mm, Valve stop 2nd line, and power wheel at Max, the fps is beyond 1030 fps with the 25 g and approx 925 to 930 fps with the 33.9 MKII's. With the Power wheel setting at 3 or 4 is where I do most of my shooting which brings the 33's to about 840 to 885 fps. I don't shoot a lot of 25g now, but when I do, I set my Power wheel below 3 and enjoy a good Impact on targets. It is still accurate at Min setting. Oh, I also have the 700mm barrel. I hope you get yours set the way you want and enjoy it to the fullest extent. The above is just a guideline and you'll have to experiment for yourself and come up with your own settings that is harmonically balanced for your gun. Good luck and stay safe.
Upvote 0