The M16A2 buttstock is about five/8" of the inch extended then the sooner models. Due to the improved size it made use of a longer buttstock screw as well as a spacer. The swivel is mounted nearer on the buttplate. This buttstock is now applied over the M16A4: The "C" https://coltcombatunitrailgun4591122.thebindingwiki.com/7765546/the_basic_principles_of_colt_combat_elite_commander_45_acp