The M16A2 buttstock is about five/8" of an inch extended then the earlier designs. Due to enhanced length it employed an extended buttstock screw plus a spacer. The swivel is mounted closer to the buttplate. This buttstock is at the moment used around the M16A4: Up for sale can be https://pulsardirectory.com/listings12980333/a-review-of-colt-python-6-for-sale