I've been fighting short stroking problems with the BOHICA Pistol (top) for over a week; since I put the Osprey Defense piston in it, it just wouldn't run reliable ... I originally had it on a 16" gun and it worked great. I finally called them on Friday and told them my story, that it's been short stroking and I've tried everything from different ammo, shortening the buffer spring and even opened up the port in the barrel; no matter what I did it might or might not run for a bit with one ammo but not another ... It was maddening ... The tech said the problem is that their system isn't reliable with a 10.5" barrel but 11.5 and up is good. The pulse from a 10.5"and shorter barrels just isn't long enough, but that they are working on a system for a 7.5" barreled upper

I really don't want to put a longer barrel on this gun so I switched it back to D.I. And now it works great again ... I put the Osprey piston system in my M16 which does have an 11.5" barrel ... and the piston system works great in it as well.