A few years years back I picked up a m16 upper at the creek. It has forward assist. It is coded to have a chrome chamber, but not the bore. I think it's a 1 in 12 twist. Now I am wondering what would be historically correct way to assemble this upper? For now it's been on a dpms lower a2 stock, dpms ar15 bolt, but I just got a fn m16a2 barrel 1 in 7 twist and I think I would like to transfer the new barrel to the dpms lower. I also have a shorter early type buttstock, pistol grip without the extra bump (a1?), and three prong flash hider. I think Nodak has a more correct lower I could buy.
Guess I'm wondering if my short stock, upper, and three prong flash hider go together? Or what to buy to make it most historically correct or at least in appearance?