well...i do my own gunsmithing and i have built my own tac 20 and i would suggest you either go with that or the practical. the pratical has the same sholder angle as the 223 23* and the tac 20 has a 30* sholder. so if you are going to do it just doit in Tac 20 you wont be dissappointed. i love mine. when i build another 20 it will either be a 20-223IMP or a 20Br.