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Hatsan Bullboss weak?

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Gambler

Gambler

Member
Feb 20, 2023
206
88
Åmot
Hi, i bought a Hatsan Bullboss .177 to upgrade from my snowpeak m25 (regulated 115bar), Bullboss i rated to 1170fps with probably a low grain pellet, the lowest pellet i got is a 8.5gr and it only show 940-980fps with full airtank. I shot those same pellets @900 with the m25, that not much of an upgrade =/ the bullboss is a hell of lot louader too, so by the sound of it it should fire way better.

So my question is is 955fps isj with 8.5gr normal on a gun rated 1170fps?
 
You wouldn't want 1170 fps if it could do it. If you are a bit of a mechanic, there are threads on making the Hatsans more air efficient. Basically the transfer port is way bigger than needed and the hammer spring on the heavy side for a 20 ft lb .177 rifle. 900 to 950 fps is a good place to be with any pellet, but you will get better downrange accuracy with a 10.5 grain pellet that starts out a little slower because of better airodynamics and less wind drift.
 
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I had a Bullboss in .25 and a AT44 in .22. The Bullboss was stupid loud. The I.D. on the inside shroud baffles were much larger than the AT44. I swapped the .22 ones into the Bullboss and it made a big difference. Check the ID on yours. I think they make them to just fit .177 to .25 now. Smaller holes make them quite. It's been years since I owned them but I had higher FPS at a mid fill vs full. Shoot it down on psi and see if it goes up. Common in non reg'd guns.
 
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sure, breach or transfer port. is it by your face? bullboss also has a hole in the rear of the shroud to vent so you could be hearing or feeling that. never a bad thing to check or replace a seal if in doubt. but even at that, if the HS is too high it will be loud. on mine I can tune it by sound and be pretty close. the bullboss is tricky to adjust so you have to follow the manual.
 
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ok, well there's no way of knowing if he touched anything. so, bullbosses have had issues with the debounce arms so that's a possible culprit. when that happens the 3 things to look at are the debounce, the valve and the hammer. unfortunately, hatsan had many changes in the bullboss and I don't know all of them. I would do a search on it as there are a bunch or threads on GTA covering issues and mods for these guns. or you can try to PM @Rallyshark . he knows these things verry well.
another quick thought, maybe the barrel isn't in right blocking the transfer port causing the valve to stay open.
 
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