Shim Guide for AAC Blackout Muzzle Brake Suppressor Mount?

[redr8er]

SIAP, but I've searched multiple forums and google and can't find the answer to my question. I'm wearing the skin on my fingers out by twisting/untwisting these things on/off with all the different shim combos. Has anyone here already put together a general shim guide?

I have a .5x28tpi for a sig 556, and a 5/8 x 24 tpi for a LWRC Repr if someone else has already shimmed these two.

[Marty916]

Just a thought but you could hand tighten down the brake, back it off untill clocked correctly and measure the gap left between the comp and muzzle shoulder. Using a caliper or micrometer you can then try different shim combinations until you get close to the gap dimension without chewing up your fingers. I'm not familiar with the AAC unit so if clocking isn't required ignore the above.

[JasonM]

unfortunately, every barrel and mount varies, so there is no type of guide.

What marty said is a good way to get close- tighten in to where you want it, and then try shoving various stacks of shims into the gap until they just wont fit.

[pcf]

If you can tell me how many degrees you are off from hand tight with no shims, I can get you in the ball park. I have all the combos written down somewhere around here.

On 28 tpi every .001" of shim equals 10 degrees of rotation. From hand tight you'll need another 15-20 degrees for proper torque. My mental math failed horribly when I said that the 24 and 28 tpi combos would be close. Here the complete list.

Shims = Degrees for 28 & 24 tpi
8 = 80 90
8 10 = 180 210
8 12 = 200 230
8 15 = 230 260
8 20 = 280 320
8 31 = 30 80
8 10 12 = 300 340
8 10 15 = 330 20
8 10 20 = 20 70
8 10 31 = 130 200
8 10 12 15 = 90 150
8 10 12 20 = 140 210
8 10 12 31 = 250 340
8 10 12 15 20 = 290 20
8 10 12 15 31 = 40 150
8 10 12 15 20 31 = 240 290
10 = 100 110
10 12 = 220 250
10 15 = 250 290
10 20 = 300 340
10 31 = 50 110
10 12 15 = 10 60
10 12 20 = 60 160
10 12 31 = 170 240
10 12 15 20 = 210 290
10 12 15 31 = 320 60
10 12 15 20 31 = 160 280
12 = 120 140
12 15 = 270 310
12 20 = 320 300
12 31 = 70 140
12 15 20 = 110 100
12 15 31 = 220 300
12 15 20 31 = 60 170
15 = 150 170
15 20 = 350 40
15 31 = 100 160
15 20 31 = 300 30
20 = 200 230
20 31 = 150 220
31 = 310 350

[redr8er]

Great stuff PCF. Thanks. I actually used the following calculation to determine the number, but I'll use your table in the future.

(1/TPI)/ 360 * degrees offset

I'm off center by about .001, but I'm not sure it will make much of a difference other than to bother me.