I own two Hesse Arms H-91 rifles. Neither of them function as designed, jams, failures to extract oreject, etc. I have learned a lot about these rifles, and the tolerances they require to operate. Mostly because I hear Hesse Arms went out of business, and re-branded themselves as Vulcan Armament, who will not work on Hesse rifles. In fact, most of the major gunsmiths around refuse to work on Hesse Arms rifles. The headspacing is wrong on both of these rifles. In a worst case situation this could be dangerous to the shooter. You can measure this by “bolt gap”, which neither has any gap. If the barrel and trunnion are mounted correctly, you can fix this by swapping rollers, but in both cases, the barrel and trunnion are installed incorrectly. Finally on the last H91, besides haveing the trigger pack and lower grip frame mis-aligned, the barrel was a shot out surplus barrel of a full auto G3, you can tell this because in areas the rifling (what’s left of it) is melted. Oh, then there is the pitting from the chamber to the muzzle. The chamber pitting makes it harder to extract rounds. I mean, there is used, then there is worn out. Unfortunately, I have no legal recourse. However, I picked up a Century Arms C-93, a 5.56 version of the rifle, and had similar problems and wonder if Century Arms sub-contracts out to Vulcan Armament. Century Arms guns are hit or miss, I have gotten some really nice rifles from them, (Wiselite Sterling, Elk River AK74) that work awesomely, and a few not so much, like the C93.