well after searching for a 10 round kit and having no luck, i wound up buying a 30 round kit. but i live in maryland where i cant receive or buy mags over 20 rounds, so i posted on the PA HTF and had a guy willing to receive the package for me. so while at it i order a BDM. well it was the best 211 shipped i have ever spent, i went to PA and picked the kit and mag up. but before i even put it in my ar i cycled it in my hands for about an hour or so. if i had to guess i would say i cycled it about 300 times with no oil. well after this the rails looked and felt very smooth, so i oiled it up and installed it in the ar. today i went to the range and fired it with federal buck ammo, the first mag was the ceiner mag and no jams or malfuntions at all. i put over 500 rounds today and the only malfuntions there with the BDM mag when someone rest the gum on the mag as a mono pod. if this had not been done it would have run all 500 rounds just fine. but 4 or 5 jams in 500 round fors a new kit ant bad, and once again it only jamed when the gun was resting on the mag