I am putting together a semiauto retro M16A1 (603). Using a lower that has the full fence. Upper is a Colt M16A1 with forward assist only. My question is which flash hider and stock set would be correct for the full fence. I have three prong and bird cage hiders. Also I have no trap (mottled) and early trap door stocks. The dates for change over are a bit illusive. Thanks for the help. I am aware of the forge code issues but am not concerned about this.