I took the upper off my M-16 and put a colt 9mm upper on her.I have some trick inserts for the mag well that allows the mag well to except colt 9mm magazines.But it seems the upper was not made to go on a M16 lower.seems the bolt when it comes back top bring the hammer back cuts into it and kinda drags across it.I called colt.they will not talk to any one about full auto.am trying to find some one around that I can look at a dedicated colt 9mm upper and lower,and see what I need to change.seems alll the agency have are M-4s and MP5s in 10mm..any one know what is differnt about the 9mm lower vs the m16 lowers???
