Muzzle brake mount install?

[Slick]

As usual, things which seem to go easy for others give me problems, and I am having trouble installing the muzzle brake mount on my BCM MK12 MOD 0 SPR upper.

Using the supplied crush washer, the brake makes contact with the washer with at least 270 degrees of rotation left to properly index the brake. I can only get it to turn a few degrees after that with a large adjustable wrench on the webs of the brake, as recommended in the instructions, nowhere even close to indexing the thin web at TDC.

Also the flats of the webs are not parallel, so using the adj wrench to tighten seems to put uneven force on the ribs, so I was reluctant to go gorilla on it without asking.

Another issue specific to this build is how to secure the barrel without disassembling the upper: there is very little barrel forward of the FSB to clamp in a vise.

Any advice, either on how to get the crush washer to crush or, relatedly, how to secure the barrel would be greatly appreciated!

[bigbigpig]

Use shims to get the muzzle brake to line up in place. Here's what I bought from McMaster-Carr to do mine. I only used a few out of all of these.

97022A450 Type 316 Stainless Steel Shim .020" Thick, 1/2" ID, 3/4" OD, Packs of 10 $7.44
97022A380 Type 316 Stainless Steel Shim .010" Thick, 1/2" ID, 3/4" OD, Packs of 10 $6.49
97022A333 Type 316 Stainless Steel Shim .005" Thick, 1/2" ID, 3/4" OD, Packs of 10 $5.78
97022A237 Type 316 Stainless Steel Shim .002" Thick, 1/2" ID, 3/4" OD, Packs of 10 $4.71

You can try a receiver vise block to hold it in your bench vise.