The US Military has used three different types of washers to keep a muzzle device in place:
- Lock Washer was used from the beginning, until about 1984. Does not allow timing choice.
- Peel (Split) Washer was used for timing the A2 flash hider, and historically correct for all M16A2 models. Both the highest quality, and hardest to install option of all the washer types. The only washer used by precision shooters.
- Crush Washer is what we use today. Fast, easy, super flexible and very secure. Should not be used with suppressors.
This is what I needed, but in Nov. 2020, I ordered a m16 buttstock w/ no trap door (order #6744). At the end of Nov. 2020, I received handgurards instead of the buttstock & no refund to make up ythe difference in price.