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 Could this cause accuracy and consistency issues in an AR10? 
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Well I think I may have finally figured out why I’m not getting the consistency and/or accuracy out of my Mega Maten AR10 build. I was blaming it on a bad Mega barrel until recently. I was removing the muzzle brake because I wanted to try something different and I discovered this!

It looks like a crusty carbon build up has been deposited on the inside of the brake threads. I tried cleaning/removing this metallic concrete type of cruddy build up out of the threads but nothing I’ve done so far has been successful. I believe this build up occurred because I used a jamb nut to secure the brake to the muzzle of the barrel rather than threading the brake all the way on to the muzzle until it seated flush against the crown of the barrel. The jamb nut effectively left a void section of threads on the inside of the brake. Anyway, that is my theory. Please see the pictures below and tell me what you think.

QUESTIONS.....?

Do you think this deposit occurred because the brake wasn’t seated flush with the crown of the barrel (due to using a jamb nut)?

Do you think this crud build up is significant enough to affect and diminish the accuracy of the barrel?

I noticed some of the carbon crud build up on the crown as well. The picture shows a lot of fibers from the cloth I wiped it with so please disregard those. Does the crown of the barrel look like it will be okay for me to install a new brake?

Anyone have any ideas for methods, products or tools that would remove the carbon crud build up seen in the pictures?

I’ve always held the Mega brand in high regard but became very disappointed with this barrel sometime last summer. It started out satisfactory enough but I wouldn’t consider it satisfactory now. The specs on the barrel are listed below the pictures.

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Mega 308 Barrel – 18 - $310 ($294.50)
• Manufactured under the strict supervision of Mega Arms.
• Chambered in .308 Winchester
• Machined with a Medium Contour.
• 1:10 twist for accurate overall performance.
• 5/8-24 threaded muzzle.
• .750 diameter gas block seat.
• SR-25/DPMS pattern barrel extension.
• 11° target crown.
• Uses standard AR-15 Mid Length Gas system.
• GUARANTEED TO SHOOT SUB 1 MOA @ 100 YARDS WITH MATCH AMMO!!
• Made from 416 Stainless Steel
• Finished in Black Nitride Coating
• Weight 44.4 oz


Last edited by old11bravo on Sun May 06, 2018 5:08 pm, edited 1 time in total.



Sun May 06, 2018 4:58 pm
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Have you shot it without the compensator? If the accuracy/precision any different?


Sun May 06, 2018 5:03 pm
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Give me the brake tomorrow. I'll take it home and run it in the ultrasonic cleaner overnight. Should remove the build up.

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Sun May 06, 2018 5:29 pm
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I don't think that small amount of crud buildup has anything to do with the accuracy of that system; I've seen much worse on rifles that shoot very well. Naturally fouling like that will build up in any gap like that between a muzzle and brake or flash hider; a common A2 birdcage is one example, but it will take many thousands of rounds (if ever) for the fouling to build up to the point of hurting accuracy.

One possibility for your accuracy problem though might be the jam nut. You should always install a brake against the barrel shoulder or the muzzle, not against a nut like that. The nut can allow the brake to be inconcentric with the bore, and that can definitely affect accuracy.

If that were mine, I'd clean the brake threads out with a 5/8"-24 tap, but without that you'll have to use a pick of some sort to reach in there and scrape it out of the threads. You could try soaking it in something like Kroil or Hoppes #9 for a few days, but I doubt you'll find anything to actually dissolve that stuff.
The muzzle needs a cleaning but looks fine otherwise; I'd try some OO steel wool under your thumb, just rotated against the muzzle.


Sun May 06, 2018 5:30 pm
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Meh. That looks fine to me.

I would try shooting it without the brake, though, to see if accuracy is better. If it is, then you have a starting point.

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Leave it cleaner than you found it.


Sun May 06, 2018 5:35 pm
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It's the palsy you old fracker!

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Sun May 06, 2018 5:44 pm
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sinus211 wrote:
Give me the brake tomorrow. I'll take it home and run it in the ultrasonic cleaner overnight. Should remove the build up.


Done! I'll have your grip too.

Yondering wrote:
I don't think that small amount of crud buildup has anything to do with the accuracy of that system; I've seen much worse on rifles that shoot very well. Naturally fouling like that will build up in any gap like that between a muzzle and brake or flash hider; a common A2 birdcage is one example, but it will take many thousands of rounds (if ever) for the fouling to build up to the point of hurting accuracy.

One possibility for your accuracy problem though might be the jam nut. You should always install a brake against the barrel shoulder or the muzzle, not against a nut like that. The nut can allow the brake to be inconcentric with the bore, and that can definitely affect accuracy.

If that were mine, I'd clean the brake threads out with a 5/8"-24 tap, but without that you'll have to use a pick of some sort to reach in there and scrape it out of the threads. You could try soaking it in something like Kroil or Hoppes #9 for a few days, but I doubt you'll find anything to actually dissolve that stuff.
The muzzle needs a cleaning but looks fine otherwise; I'd try some OO steel wool under your thumb, just rotated against the muzzle.


Thank you! I will try these suggestions.



MadPick wrote:
Meh. That looks fine to me.

I would try shooting it without the brake, though, to see if accuracy is better. If it is, then you have a starting point.


Another great idea. Half the battle (or maybe more) is finding out where to start.

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Haha lol! I'm still trying to figure out how you got your typewriter to transcribe to the internet.


Sun May 06, 2018 6:07 pm
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I'm certainly no expert, and others here are more versed than me on ARs, but that metal build up looks copper colored, almost like pieces of jacket have been hitting it. Now that could just be copper fouling from the muzzle I suppose.
What's the purpose of not seating the brake fully? Seems they were designed to be used threaded all the way on, but I'm not familiar with that particular model, so maybe not?


Sun May 06, 2018 6:21 pm
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Why did you use a jam nut? Are the threads inside of the muzzle brake not long enough to allow the muzzle brake to seat fully against the shoulder of the barrel's muzzle end?

I have the same barrel on an AR10 build with zero accuracy issues, but I did use the PWS FSC30 muzzle brake on it. It uses shims to time the brake to the barrel. From what I remember there is plenty of thread inside that brake.

Sorry you are having issues with yours.


Sun May 06, 2018 7:34 pm
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Normanator wrote:
I'm certainly no expert, and others here are more versed than me on ARs, but that metal build up looks copper colored, almost like pieces of jacket have been hitting it. Now that could just be copper fouling from the muzzle I suppose.
What's the purpose of not seating the brake fully? Seems they were designed to be used threaded all the way on, but I'm not familiar with that particular model, so maybe not?


It's common to have some copper in the fouling in/around muzzle devices. Mostly you'll see it show up as blue corrosion.


That brake doesn't look to me like it would index on the muzzle (threaded section appears too deep in the pics). You should be able to time it to the barrel with shims, as waglocker said. I'm assuming timing is why you used a jam nut; that's acceptable with a flash hider (bigger hole for the bullet to pass through) but not with a brake.


Sun May 06, 2018 9:08 pm
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Quick question...what ammo are you using?

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Sun May 06, 2018 9:11 pm
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Have you consider it might be the operator head space and timing? Drink water, change your socks.

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Mon May 07, 2018 5:02 am
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Yondering wrote:
One possibility for your accuracy problem though might be the jam nut. You should always install a brake against the barrel shoulder or the muzzle, not against a nut like that. The nut can allow the brake to be inconcentric with the bore, and that can definitely affect accuracy.
...


That right there. Get a set of shims and install the FH correctly.

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Mon May 07, 2018 6:57 am
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RocketScott wrote:
Yondering wrote:
One possibility for your accuracy problem though might be the jam nut. You should always install a brake against the barrel shoulder or the muzzle, not against a nut like that. The nut can allow the brake to be inconcentric with the bore, and that can definitely affect accuracy.
...


That right there. Get a set of shims and install the FH correctly.

Gonna try shooting without a muzzle device first but when I do re-install the muzzle device you can rest assured that I'm done with the jamb nut method.

BadKarma wrote:
Have you consider it might be the operator head space and timing? Drink water, change your socks.

Haha lol, yes this has been considered.......... and not completely discounted as of yet. Thank you for your valuable input.


Mon May 07, 2018 1:14 pm
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jukk0u wrote:
It's the palsy you old fracker!

So much helpful advice here on WaGuns... :ROFLMAO:

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Mon May 07, 2018 1:21 pm
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