THIS will work. This is the way I've done them since my first build/assembly in the late 80's. The military manual was all I had. The later builds have all been pre-assembled uppers. Although I do now own a receiver block, I have never used it. I agree the receiver block is probably the BEST way to go but the old school method in the mil manual will work fine. Also someone mentioned aluminum scuff marks on the barrel when you're done--take some steel wool and WD40 to it--20 seconds and you're done.

