There is a big following of Cmmg lpks. There are people who will buy those kits over any other better kits. I've used these and they work. But I've had the most problems with cmmg over other lpks such as rock river, stag arms, spikes etc. It's more about slightly out of spec pins which are hard to get in or that missing detent pin. Of course this is my opinion. I've just had more problems with cmmg than the others I listed. I've also had lpks from cmmg that just worked too.