How much distance travel with each rotation on MD?

[nimdabew]

Hi all. I am doing this purely as an aesthetic hand guard/muzzle device spacing. I have an SPR/M4 and I want to get a 11.5" hand guard on a 14.5" barrel. I know that my previous 12.5" build and 9.55" hand guard (Mk18) left about a .15" gap between the suppressor and hand guard so I was thinking of getting a 11.7" hand guard instead and using shims to move the flash hider out a little further to make up that extra .05"-.1" of gap between the back of the suppressor and the front of the hand guard.

Does anyone have a bare barrel, set of calipers, and a few minutes to tell me the total distance travel of the flash hider per rotation so I have an idea of how many shims I would need to use to make the proper clearance from hand guard and suppressor?

Side note, is there a maximum number of shims that one can use before it becomes unsafe as far as bore alignment with use of a suppressor?

ETA: The shims I plan on using have a large 180 degree shim, eight 90 degree shims, and a single 45 degree shim, hence the need of distance travel per rotation. I can get a total of 945 degrees of rotation if I used all the shims, but that seems like it would be pushing it to me.

Also, is there a minimum length that you, as a shooter, would feel comfortable with, between distance of the hand guard and back of suppressor while shooting due to barrel flex etc?

[Clint]

This one is easy, no calipers required.

1/2-28 threads, 28 threads per inch.

1/28 inches per thread or .0357" per revolution.