The M16A2 buttstock is about 5/8" of the inch for a longer period then the earlier products. Due to the elevated size it applied a longer buttstock screw in addition to a spacer. The swivel is mounted closer into the buttplate. This buttstock is presently applied within the M16A4: AR15.COM https://bersa9mm12222.kylieblog.com/31760272/the-basic-principles-of-gold-cup-trophy-colt-45