Pin/weld muzzle device wiggles

[WalterJones]

My muzzle device has some play, or wiggle in it. Is this a problem?

Had a muzzle device pinned and welded recently, to a 13.5" barrel, 6.5 Grendal. Couldn't find a gunsmith in my area willing to do a pin/weld job.

So I got with a certified welder friend who was willing. Did double pins just to make sure. Drilled through the muzzle brake and then in to the threads. Beveled the pins to match the drill bit, using tool steel pins cut to below flush. He fused them in place with a TIG welder then put a bead over the top.

Has enough play that I can feel it wiggle a little by hand. Should I be concerned? Or will this be fine?

I couldn't find a long enough brake to get the required 16" lenght. So I threw on a crush washer and it came out to around 16 1/8", so I added some shims to get it to 16 3/16" just so there's no wiggle room for an ATF spook.

Sorry for the gargantuan pics, I ran them through a program that was supposed to compress them and used Tumblr tto host. I've been trying to figure this crap out but haven't succeeded yet.

[Milsurp1]

If the barrel is too expensive to replace I would put a bore-sized dowel rod into the muzzle and make sure the muzzle brake does not come anywhere close to contacting the dowel no matter how hard you wiggle it. If it is a cheap barrel I would start over and have AR15Barrels do it even if you have to mail it to him.

[kcheung2]

I can’t tell for sure but it looks like you pin/welded the shim and not the actual muzzle device.

[WalterJones]

I guess my concerns are more around: what happens if a spook puts a breaker bar on this muzzle device and torques to destruction. Will the little bit of wiggle play assist him or have no effect?

If the barrel is too expensive to replace I would put a bore-sized dowel rod into the muzzle and make sure the muzzle brake does not come anywhere close to contacting the dowel no matter how hard you wiggle it. If it is a cheap barrel I would start over and have AR15Barrels do it even if you have to mail it to him.

The barrel isn't terribly expensive, a Sanders Armory match grade.

The muzzle brake is for a .308/30-06 so already over bored a bit but I'll see if I can find a dowel and make that happen.


The bead is centered on that raised band on the rear of the brake. For whatever reason the welder also decided to take it over to the crush washer.

[baih777]

The welder put the spot weld and pin too close to the washed.
The washer got hot and now has no tension.

[WalterJones]

The welder put the spot weld and pin too close to the washed.
The washer got hot and now has no tension.

So basically the heat from the weld softened the temper on the washer?

Makes sense.

[Bullets&Whitewalls]

Yup hitting that washer is what caused it to come loose. I’d be concerned that it will start getting looser as time goes on. Also running over it twice didn’t help it. The first one I ever did I tacked it twice and it eventually loosened up. If I do them now it’s one quick tack and done. The less heat the better.

[The War Wagon]

You'll shoot it free, in time. Accuracy will suck UNTIL then.

[baih777]

Where do you live. We have a gunsmith here in SoCal.
That will drive you nuts knowing it loosened up.

[beanz2]

It’ll probably mess with your barrel harmonics. Shoot it for groups and see how it goes. I used to have a Bren 805 with a wiggly extension. I was getting 6-8” groups at 100 yd. Fortunately I left the state and now it’s a legal SBR.


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[ar15barrels]

My muzzle device has some play, or wiggle in it. Is this a problem?

Had a muzzle device pinned and welded recently, to a 13.5" barrel, 6.5 Grendal. Couldn't find a gunsmith in my area willing to do a pin/weld job.

So I got with a certified welder friend who was willing. Did double pins just to make sure. Drilled through the muzzle brake and then in to the threads. Beveled the pins to match the drill bit, using tool steel pins cut to below flush. He fused them in place with a TIG welder then put a bead over the top.

Has enough play that I can feel it wiggle a little by hand. Should I be concerned? Or will this be fine?

The function of the pins so to make it so the muzzle device can not be removed without damaging the barrel beyond use.
The pins should NOT be used as the feature that keeps the muzzle device in place.
They do not fit tight enough to do that job.
The muzzle device should have been tightened into place BEFORE the pin holes were drilled, the pins inserted and the welding done.

It sounds like your muzzle device was NOT tightened before it was pinned.
This being the case, the muzzle device is going to rattle on the barrel, eventually messing up the area around the pin.
This is going to effect accuracy immediately as a rattling muzzle device is NO GOOD for accuracy.

All is not lost, but the muzzle device probably is.
The muzzle device should be removed by grinding through the welds until the pins can come out.
Then a new muzzle device should be tightened into place properly and a new perm attach job done in a different location so that the oversized holes that are already there are NOT used for the new perm attach job.

[ar15barrels]

The bead is centered on that raised band on the rear of the brake.
For whatever reason the welder also decided to take it over to the crush washer.

Depending on how much heat the welder put into the crush washer, that's probably the reason it loosened up IF it was properly tightened in the first place.
A crush washer is a thick flat spring.
If you heat a spring up to welding temperature, you definitely lose the spring properties that it had from the much lower tempering that was causing it to be a spring.

Welding heat should NEVER be put into a crush washer.

[SISKIN]

Listen to Randall- He's the man...

[PachecoFTW]

Wow and I thought my weld spot was ugly, I barely got discoloration but 500 rounds later still solid.

[WalterJones]

Thanks, Randall, I appreciate you taking the time. At this point I'm considering just putting on a 16" barrel and be done with it.

Wow and I thought my weld spot was ugly, I barely got discoloration but 500 rounds later still solid.

Well, the welder is a certified master welder and did exactly what I asked of him. I wanted it to be obvious that the welds were there. Extending the bead to the crush washer was his idea, though, and I can't fault him since he's not a gun smith and neither of us knew any better.