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 Post subject: Bad Muzzle Device Install?
New postPosted: August 10th, 2014, 9:43 am 
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Joined: April 26th, 2012, 1:24 pm
Posts: 13
Location: Gilbert, AZ
I have an ACR that I had cut down to 12.5". I didn't have the muzzle device in hand when I had the barrel cut to have the smith install, so when I got my AAC 51T Brakeout I installed it myself. AFAIK I followed the install instructions to a "T".

Prior to having my barrel modified, I was able to squeeze about 1"-1.5" MOA at 100 yards with this rifle. Shooting it now, my shots are somewhat all over the place.

Before installing my Brakeout I inspected the barrel and noticed nothing wrong with the Gun Smith's work. (He's a very well known Smith who has done a lot of ACR and SCAR barrel chops.)

So my question is, did I do a poor Brakeout install? Is there anything I can do/try to remedy this or is there a good local gunsmith near Gilbert that can fix my issues?

Thanks guys!


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 Post subject: Re: Bad Muzzle Device Install?
New postPosted: August 10th, 2014, 9:50 am 
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2 things:

Was the muzzle re-crowned after being chopped?

Is it a registered SBR?

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 Post subject: Re: Bad Muzzle Device Install?
New postPosted: August 10th, 2014, 10:06 am 
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Location: Gilbert, AZ
ynotaz wrote:
2 things:

Was the muzzle re-crowned after being chopped?

Is it a registered SBR?


Yes and yes.


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 Post subject: Re: Bad Muzzle Device Install?
New postPosted: August 10th, 2014, 10:23 am 
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Joined: August 7th, 2014, 8:31 pm
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Location: GIlbert, AZ
Take the mount off and do some testing if you have not already done so. Just make sure you clean the threads well before attempting to screw the muzzle device back on afterwards. If groups return to normal after taking the brake off then chances are you have found your source of the issue.

If you have a spare device around you can throw that one on there if the barrel shoots normally without a muzzle device. In a few cases the AAC mounts have been known to alter the accuracy of the host for the worse. Often it has to do with just receiving a bad mount, it happens and AAC will take care of you. Just troubleshoot it on your own and then have your smith take a second look at it before getting AAC involved so you can rule out something on your end.


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 Post subject: Re: Bad Muzzle Device Install?
New postPosted: August 10th, 2014, 10:28 am 
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Joined: April 26th, 2012, 1:24 pm
Posts: 13
Location: Gilbert, AZ
Thanks for the advice. I'll be sure to try it and see what happens. As it happens, I actually do have a spare Blackout waiting to go on my SCAR so I could test w/ that if need be.

Sorry SCAR, you've always been on the back burner lol.


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 Post subject: Re: Bad Muzzle Device Install?
New postPosted: December 21st, 2014, 1:08 pm 
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Were you getting those results using the exact same MD prior to cutting down the barrel? If so, (just speculating here) maybe that the new crown, shoulder, and/or threads are not concentric/perpendicular to the bore and throwing things off. You might spin each MD on the barrel right up to the shoulder with no shims and see if everything looks even all the way around (just be sure everything is clean/degreased).

For checking it out on the range, I would do a 10-shot group @ 100 yards from a rest (preferably with magnified glass) with no muzzle device and see what you get.
Then do 2 more 10-shot groups, each with the 2 different MDs (same day/conditions/ammo/etc.). Again, just make sure both barrel and MD threads/surfaces are clean. If you need/want to worry about timing them, install each with new shims or peel washers (not crush washers), and torque to minimum values. If you don't need to worry about timing, I'd run them right up to the shoulder with no shims. That should help isolate the issue.

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 Post subject: Re: Bad Muzzle Device Install?
New postPosted: April 21st, 2015, 2:53 am 
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Joined: April 21st, 2015, 2:40 am
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freefly wrote:
Were you getting those results using the exact same MD prior to cutting down the barrel? If so, (just speculating here) maybe that the new crown, Paris shuttle transfers shoulder, and/or threads are not concentric/perpendicular to the bore and throwing things off. You might spin each MD on the barrel right up to the shoulder with no shims and see if everything looks even all the way around (just be sure everything is clean/degreased).

For checking it out on the range, I would do a 10-shot group @ 100 yards from a rest (preferably with magnified glass) with no muzzle device and see what you get.
Then do 2 more 10-shot groups, each with the 2 different MDs (same day/conditions/ammo/etc.). Again, just make sure both barrel and MD threads/surfaces are clean. If you need/want to worry about timing them, install each with new shims or peel washers (not crush washers), and torque to minimum values. If you don't need to worry about timing, I'd run them right up to the shoulder with no shims. That should help isolate the issue.


Thanks for the remark. i am also face same froblem so your post is more helful to me thanks.


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