Shim pack for timing muzzle brakes on 450 Bushmaster uppers  (11/16 x 24 TPI)
or M-14/M-1A gas systems snug to the barrel

If you are trying to use shims to time your brake on your 450 Bushmaster, you’ve  come to the right place to get stainless steel shims that fit!  These also work to shim the M-14/M-1A gas system snug to the barrel.

This pack includes 6 shims:
one – .020 thick shim (marked blue)
one – .010 thick shim (marked red)
two – .007 thick shims (marked black)
one – .005 thick shim (marked gold)
one – .003 thick shim (marked green)
​
ID: .687″ (+.005 / -.000)
OD: .873″  (+0  / -.005)
Thickness +/- .0005
​18-8 Stainless steel

On the 450 Bushmaster, you may need 2 packs depending on how far out of time your brake is.   On brakes that cannot be more than 90 degrees out of time, one pack usually suffices.   As an AR upper comes from Bushmaster, .556 and 30 cal shim packs are too small,   .338 Lapua are too big.  The factory gets around this by using a crush washer.  Crush washers are a bad Idea if you are planning on hanging a can off the end of the barrel.   Use these shims and have some peace of mind!    Always recommend using a good thread locker like Rock Set or ‘red’ thread lockers when affixing muzzle devices.

These may work for the 458 SOCOM, 500 Beowulf, etc. Per Badger: “I don’t have one to try.   Check the threads OD and if its under .687 these should work!”