The M16A2 buttstock is about 5/8" of the inch for a longer time then the sooner types. Because of the increased length it applied a longer buttstock screw and also a spacer. The swivel is mounted nearer on the buttplate. This buttstock is currently made use of within the M16A4: https://colt-python-6-for-sale06026.blogpostie.com/53190738/the-2-minute-rule-for-colt-python-6-for-sale