I have an A1C7 upper that I am going to build up and was wondering if it took an A1 or A2 lower. I have two NDS black A1 lowers on the way and was thinking on using one with this build. Did they use A1 or A2 stocks? It seems they are kind of transition type of upper and was wondering if they had diferent configurations as the transition to the A2 came along. Which hand guards would be correct, triangle or early shinny round? This upper has a teardrop forward assist and I thought these took the large button type? Sorry about all of the questions but would like to get it close to the original. I am kind of doing a progression collection. One slick side, one A1 with forward assist, then this build with the forward assist and bump, I have a Colt 6600. for my A2. Any suggestions would be great. I think I am starting to have a problem, every time I think that is enough another build pops in my head that I need.