Re: Spring washer
So, lets talk about this a bit.
The only time that a lock washer is really needed for a thread on .556 is for full auto use. This is true because in semi more, the slapping effect is absent. For the vast majority of users a simple strong hand tightening is more than enough. Many actually experience quite a bit a difficulty in removal after a few hundred of semi rounds, requiring one to "heat up" through some additional firing and the use of a strap wrench. In other words, most do not need anything more than a good solid mounting without any need, even for light full auto, a washer.
For decades, when the time came for full auto mounting, the following has been done very effectively. Remove the flash hider and the hider washer. Never use the flash hider washer for mounting a can.
Use one of these, properly sized for the can shoulder, threads, and the barrel shoulder.
http://www.mcmaster.com/#rubber-washers-and-steel-washers/=d4q8yv <span style="font-weight: bold">Go to the Wedge Lock</span>. Same units as packed from the factory, providing one-way bite.
Be sure than assemble the two piece washers properly. A good, reasonably firm tightening and you are ready. Both shoulders will be locked solidly to the washer. And, yes, you will be strapping it off. These will bite into both shoulders. No damage other than they do get through to the shoulder material.
