Quote Originally Posted by RBruce View Post
Is the split washer basically a standard 1/2" lock washer that is blued? I have a commercial one that just fits over the threads of the barrel, but is nearly the diameter of the widest part of the 3 prong. The one in the photo above looks quite a bit smaller in diameter than the 3 prong.
No, it is not. It is a special split lock washer. It measures smaller than a standard one and shorter than a counter bore type for an Allen head. I know of a tall (thick) commercial version for an Allen head and the thin (Colt) version for the flash hider. Both are about .750 to .800 in diameter and one is .120 thick and the other about .080 (+-) thick.

Edit: Not blued but Parkerized.