I'm running an old Colt kit and it is quite reliable. I've handled the Ciener kits and they do seem to be more robust than my Colt one, but they do have a bit of a reputation of being a bit picky about magazines and ammunition. DPMS was making a conversion kit that looked like a complete knockoff of the Colt and they also were supposed to be coming out with some 30 rd magazines for them as well that do fit in both the DPMS and Colt kits.