The M16A2 buttstock is about five/eight" of the inch extended then the sooner models. Due to greater size it utilized a longer buttstock screw and also a spacer. The swivel is mounted nearer to the buttplate. This buttstock is currently utilized over the M16A4: I say this being a collector https://begindirectory.com/listings12983171/gold-cup-trophy-colt-45-an-overview