I bought one over a year ago. No issues with it in about 1200 rounds of various ammo from wolf to hornady. Mine has had some mods done to it in this time but none were needed to make it function. I have installed a retractable stock (the ATI f style mp5 stock for about $160, I changed out the grip frame for a navy style sef "clipped and pinned", put a German cocking handle on it cause the c93 comes with a cheap all metal one that looks like crap! I duracoated it FDE and a small amount of camo, cut down the barrel, recrowned and threaded it again, replaced the front sight, next I'm gonna install a paddle mag.
I also replaced the rollers with +4 ones cause the bolt gap was out of spec but it still ran right without that being done. Love it