I have a hatsan bull boss and been trying to tune it with a unregulated air tube I average 810fps, with a regulated hatsan air tube I average about 440fps does this seem normal?
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Hatsan bullboss .25 FPS?
- Thread starter kelii223
- Start date
I can only speak to unregulated performance on my Bullboss .25. With JSB Exact Kings (25.39 gr) mine starts out around 890 fps, and after 18 shots (2 magazines) I am getting 850 fps. The fps stays up above 870 through the first 14 shots, then the drop off begins. What pellet are you shooting, and what is your regulator set to? Have you made any hammer spring adjustments? 440 fps seems like way too much drop off for using a regulator. Share some more info with us, and maybe we can help you sort this out. By the way, I also own an FX Streamline 25 and an FX Crown 30, and the Bullboss gets as much trigger time as they do. It's just plain fun to shoot!
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Hi thanks for the reply so I’m shooting jsb kings 25grain. The unregulated tube accuracy suffers at 50 yards so I been shooting the regulated tube cause I get good groupings at that yardage. There is no wind at all also we wash,dry,inspect and weigh our pellets.
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The max recommended fill pressure on the Bullboss is 200 bar, or about 2900 psi. Depending on what your regulator is set to, that may not leave a lot of wiggle room before you come off the regulator. I'm still concerned about that 440 fps. That is awful low. What is your regulator set to? Also, what size groups are you calling good groups and bad groups? I'm not trying to nitpick, but I would like to know what your frame of reference is. I accept that my Bullboss won't group like my Streamline does, but I routinely get one-inch groups at 50 yards with it. Also, you should pull the o-rings from your magazines, then try pushing pellets through each hole. Mark the ones that seem to drag, find out where the rub point is, and hit it with a Dremel tool so the pellets pass smoothly through. This will help a lot with accuracy. Next, give that barrel a good cleaning if it hasn't had one recently, or if you haven't done it at all since it was new. Lots of good info here and on Youtube about proper cleaning techniques. After all that is done, shoot some more, and check the muzzle of the QE shroud for any signs of clipping if your accuracy does not improve. Lastly, have you worked on the trigger any? From the factory, the trigger pull is sometimes a bit much. I dialed mine down a bit and my groups tightened right up. If you make any adjustments, follow the manual, and make VERY small adjustments at a time.
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