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View Full Version : "Roughage" on barrel crown? (AR15; now with pics)


GettoPhilosopher
09-24-2011, 1:18 PM
Got my new Spikes 16" Midlength today (bought it used off a Calgunner). I'm going to be running it on a featureless build, so first thing I did was to pull off the FH.

Under the FH, the end of the barrel is rough and uneven. There's a little tab of metal sticking up maybe a millimeter as well. Does that matter at all? Leave it and slap a brake on it? Do I need to file it off?

I'm pretty sure it wasn't the seller, as it's all finished. Any suggestions? I know barrel crown can be a Big Effing Deal, but at the same time...I don't want to freak out if it's one of those stupid noob questions. :P

http://i121.photobucket.com/albums/o206/gettophilosopher/IMAG0043.jpg


http://i121.photobucket.com/albums/o206/gettophilosopher/IMAG0042.jpg

PanaDP
09-24-2011, 1:51 PM
I'd have it properly crowned. A bad crown can make a rifle shoot really poorly.

MrPlink
09-24-2011, 3:17 PM
well here is the million dollar question: how does it shoot?

SanPedroShooter
09-24-2011, 3:20 PM
The crown looks okay to me. It just looks like some crap on muzzle.

GettoPhilosopher
09-24-2011, 3:23 PM
The crown looks okay to me. It just looks like some crap on muzzle.

That's what I was wondering. Crown is BFD and all, but this just looks like some crud on the muzzle. Maybe something about the finishing?

well here is the million dollar question: how does it shoot?

Just got it today. I'll be taking it to the range next Sunday. We'll see then.

SanPedroShooter
09-24-2011, 3:26 PM
I dont have a lot of experiance taking MB/FH off AR's, but it looks like some unfinshed metal or something... Does it come off? It looks like when the blank came off the lathe or whatever, they didnt file or smooth the muzzle out.

Freagan
09-24-2011, 3:31 PM
It looks like carbon build up. I just made the same sort of discovery on my AR, except mine has a build up of copper fouling on the muzzle crown. Since I am currently away from home and have no tools or even work bench to work with, so I am not really sure what to do (still haven't taken off the muzzle brake)

GettoPhilosopher
09-24-2011, 3:42 PM
It looks like carbon build up. I just made the same sort of discovery on my AR, except mine has a build up of copper fouling on the muzzle crown. Since I am currently away from home and have no tools or even work bench to work with, so I am not really sure what to do (still haven't taken off the muzzle brake)

I assumed it wasn't buildup because it blends so well with the muzzle. If it turns out to just be carbon buildup under the FH, I'm going to have to slap myself for asking a noob question. :P

#Isweartogodthisismy3rdARbuild

Edit: *Slaps himself*. Using my trusty precision carbon scraper (Read: a Craftsman 5/64" flathead screwdriver), it came right off. I'm going to go drink away my embarrassment now. :p

SanPedroShooter
09-24-2011, 4:02 PM
Ha ha, duh.... I couldnt figure out what could cause a build up of metal like that. I figured it wasnt permanent...

-hanko
09-24-2011, 7:47 PM
A well crowned barrel should have zero rough spots at the end of the bore. You can check with a standard cotton swab...Place the swab in the barrel and pull it out...you shouldn't see any cotton fibers left around the muzzle.

-hanko

shark92651
09-24-2011, 8:22 PM
That looks like carbon build up to me - notice how the crud is spaced out about where the vents are? I see this every day as I am constantly swapping muzzle devices for customers.

MrPlink
09-24-2011, 9:10 PM
A well crowned barrel should have zero rough spots at the end of the bore. You can check with a standard cotton swab...Place the swab in the barrel and pull it out...you shouldn't see any cotton fibers left around the muzzle.

-hanko

provided it is clean, yes. Otherwise carbon can snag up a q-tip fairly easy.
Not to mention, just because your crown is smooth, does not mean it is good.