Muzzle Shims Report

Talk about the AR15 style rifles chambered in 450 Bushmaster.

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Muzzle Shims Report

Postby Hoot » Sat Feb 25, 2017 2:19 pm

A few days ago, Top_prop posted a link to a vendor selling muzzle timing shim sets for 11/16-24 threads like our 450b uses in a
different thread on this sub-forum. I ordered a set to check out and report on. They came 2 days after ordering them online!

They were packaged as advertised:

Image

The dimensions are to spec as measured with a Brown & Sharpe Micrometer. The finish is good. No burrs.

Here's the experience I had timing my Ross 3-gill brake to a Franklin Armory 450 Bushmaster 20" Hbar barrel"

Unshimmed, snugged but not torqued:

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With .020 Shim, snugged but not torqued = needs more:

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With .020+.010 Shims (.030), snugged but not torqued = real close but went past TDC when torqued:

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With .020+.010+.005 Shims (.035), snugged but not torqued = a bridge too far:

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With .020+.007+.005 Shims (.032), torqued = Perfect:

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In conclusion, the Badger Ridge Industries shim set will accommodate approximately 0 to 270 deg past TDC, but will not help with 270 to 359 degrees past TDC. You'd need 2 sets unless we can convince Tom to add 1) .015 shim to the pack. There's a second issue and that is protrusion. At .868 OD, the shims stuck out .040 beyond my brake's diameter and .065 past my barrel's diameter. The only concern with that protrusion is when pulling the rifle out of a padded case, it may hang up on the padding. It wasn't enough that I would worry about it snagging on brush as I passed through cover though.

Hoot
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Re: Muzzle Shims Report

Postby Bmt85 » Sat Feb 25, 2017 2:34 pm

Great report!
I ordered 3 a couple days ago, should be here Monday. Kind of sucks they protrude that much, but could be worse. At least we now have something to time our muzzle devices.
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Re: Muzzle Shims Report

Postby plant_one » Sun Feb 26, 2017 2:25 am

sure would be awesome if he could tone down the OD to match rosses brakes - i bet he'd sell a gaggle of them then! :)
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Re: Muzzle Shims Report

Postby Top_prop » Thu Mar 02, 2017 9:12 am

Bmt85 wrote:Great report!
I ordered 3 a couple days ago, should be here Monday. Kind of sucks they protrude that much, but could be worse. At least we now have something to time our muzzle devices.



I agree. Its better than nothing. My brake, from SD Tactical has a larger OD so they are rebated for the most part. Though the BadgerRidgeInd.com round shims do protrude beyond the 3/4" flats used to snug the brake down. At least its timed, straight, and solid.



Like Hoot, I had to vary the thicknesses to get it right... but it worked out with one pack. My SD brake doesn't have a top nor bottom... they are both the same, so it could never be more than 90 degrees out of timing. If the brake has a bottom to it, you may need a second pack.

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Re: Muzzle Shims Report

Postby Hoot » Thu Mar 02, 2017 9:40 pm

Forgive my ignorance, but is that one of those brakes that doubles as a QD mount for a suppressor as well? Trying to understand the reason for the rings.
If the protrusion bugged me enough, I'd eight chuck the barre in my hobby lathe and turn them down for a minute's worth of effort, not including truing. Otherwise, figure out a mandrel to hold them with and chuck it in the drill press and have at them with a file. Might not leave enough meat on the bone though, especially with the thinner ones.

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Re: Muzzle Shims Report

Postby plant_one » Sat Mar 04, 2017 10:16 am

Hoot wrote:Forgive my ignorance, but is that one of those brakes that doubles as a QD mount for a suppressor as well? Trying to understand the reason for the rings.

Hoot



yes it is. its SDTA's adapter for their QD tailcap for their solvent trap's that can be form 1'ed into suppressors.

i would have to speculate that the reason for the rings would be indexing the brake for use when not running suppressed. from what i read, they're supposed to be a fairly decent brake when used as a standalone.

i considered going their QD route, but i haven't gotten annoyed enough yet at threading mine on and off all the time yet to make the jump to QD mounts :mrgreen:
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