I'm pretty new to the AR platform. I just recently bought an AR build (used parts). Everything works great, I just noticed some pretty heavy copper build up at the end of the barrel. It's so thick, a q tip won't get it. It's hardened.
1. Will a brass brush ruin the crowning?
2. Do I even need to clean it off? I'm not trying to sharp shoot with this thing but (of course) I do want decent accuracy inside 100 yards.

I use Hoppes #9 for copper fouling along with plastic brush and copious amounts of elbow grease. In for info on other methods.

Normal bore cleaning clears the crown where the bullet contacts.

My choice for cleaning copper. I prefer Boretech’s entire line for all my cleaning.

From my experience, only a specific copper removing cleaner actually removes copper.  

I use "Shooters Choice" copper cleaner.  Works fantastic.   Run a patched soaked with the cleaner through the bore.  

Let it sit per the instructions, then clean out with solvent and patch dry.  I assume on the crown, dab it with a q-tip and copper cleaner.

Before:

After:

Welcome to the site and the AR platform Op, it gets addicting and there's a ton on info out there. I highly recommend checking out some videos on general cleaning and lubing of the AR. Mr guns and gear and Iraq Veteran 8888 are two guys I know that have some good videos on that. Keep your rifle lubed up and it'll run a long time with general periodic cleaning. Tell me more about your build you got, like what kind of barrel?

#1 A brass brush is much softer than bbl steel. It can't harm it. I stick with brass for the bore, even patch holders and brass stems. ProShot offers all brass brushes. Use a chamber brush for the chamber when general cleaning. Just be careful not to use sectional metal cleaning rods(Basically I wouldn't risk another steel coming into contact with crown and bore).

#2 I like to use a strong copper cleaner like Sweets for copper remove every maybe 1k  on my precision rifles but I'll always do Mpro7 cleaner every few hundred for general cleaning. Followed up with Mpro7 Lpx oil. Cleaning regularly and using an oil like Lpx or CLP will keep the deposits down, I generally don't use a copper solvent unless it's a precision build and accuracy has dropped off.

Thanks for the replies! I've always had handguns and shotguns but this is my first "battle rifle" and it's freakin awesome. I love this platform.
I want to be clear, the copper build up is on the tip of the barrel (by the flash hider), not inside. I'm not too worried about the inside, what the bore snake picks up is good enough for me. It's the caked crap at the end... I've never seen that before. I'll post a link to a picture ( can't figure out how to just upload an image). It's not a cooper color anymore because after shooting I tried spraying some CLP and tried to get after it with a long trip but all it did was make it black and shiny. I guess I'll need to take off the flash hider. I've heard I'll need a new castle nut every time I'll remove it? From the replies, a brass brush will be safe to scrub with...

JASONM4-
Good info here, thank you.
I had a buddy of mine build it. I'm not exactly sure what kind of barrel, like, I don't know the brand. All I know is it has a 1:8 twist. I don't think it's chrome lined. I think he said it was just like a 200 dollar barrel. He had a complete aero precision lower and stripped upper he said he'd sell me and I asked him to look around for any other parts I'd need. Turns out he had everything he needed to build a complete rifle, shy of a gas block and iron sights.  After he ordered those, he put it all together. Works great. No malfunctions 👍

Sweet's 7.62 is one of the best copper removers I have found.  I just don't want to leave it in the barrel too long, and when it is done doing it's job, I go out of my way to clean it out with something like Hoppes, then rubbing alcohol, and finally a light coat of oil followed by a clean white patch.

You're welcome. And it sounds good, try some different ammo and see what kind of accuracy you can get.

Looks like some carbon on the crown. Honestly the build up is self limiting and shouldn't be a problem or affect accuracy. I really never clean the crown and typically there's no reason to.

If you really want to remove the buildup though, you can use a small brass pic/scraper or a sharp wooden manicure(cuticle) stick, which won't hurt the barrel. I would use a good solvent or CLP and let it soak on the crown for a bit, it should come right off. I wouldn't use anything else or remove the muzzle device, you should be able to get in there using one of the above scrapers. But if you want to take it off, you need to replace the crush washer behind it, it's a one time use item.

(By the way, to show a Dropbox pic you need to use IMG tags instead of URL tags. Also remove the "dl=0" at the very end of the link and put "raw=1" instead.)


Op's picture

Our service rifles barrels have gone well past 3000 rounds before I pulled the flash hider off to clean the crown. There was a cone of carbon built up that came off with the flash hider. It had a 22 caliber hole in the center and coned out to about 1/4 thick. The rifles still shot sub Moa.

Right on, thanks y'all!!


Thanks, I couldn't figure it out 😄

This.

Though if fpuling is as described, I'd go at it 1st with vigor with a brush, and maybe even JB paste first to erode out, since chemical cleaning will take a massive number of whites, ofbas described.

Doesn't look bad in the picture. I'd probably just shoot it. If you do decide to take it off remember to secure the barrel in a vice or other fixture rather than using a mag block or receiver clamshell.

I never worry about copper build up OP.  I have been shooting the AR/M16 platform for decades and have ONLY been using (with a few changes using snake oil in between before going back to) breakfree CLP.  It works well enough and keeps my sticks running.  I will use this on a cotton swab and swab out the flash suppressor area as well and call it a day.   FYI I have NO connection to the aforementioned company I merely use some of their kit.

If you want to get out pretty easy/quick use the BoreTech copper remover and nylon brushes followed by patches.  Nylon because the bore cleaner will "eat" the brass brush, too.  Just like it does the bullet jacket material you want to remove from the barrel.

Repeat the brushing with BoreTech and patches till the patches stop coming out looking like this.



The blue/green/black is the copper coming out.  The next brushing with BoreTech will look similar, but lighter in color on the patch.  The third brushing/patching will look better.  Repeat till the patches aren't that "pretty" color anymore.

You don't have to use the BoreTech copper solvent every time you clean.  Just now and then.

How many rounds fired with this rifle?  The  barrel has pretty heavy firecracking.

Don't worry. Choot it.

I 2nd this

I have a can of foaming boar cleaner that does quite well on copper, but sometimes you need a specific cleaner to target the heavy build ups.
I clean my rifle every time I shoot it, just because i dont get out to the range as much as id like, so i dont store them dirty.

Most of the really aggressive copper fouling removers have ammonia in them.
Unless you want to stink up the whole house, and have your wife/significant other mad at you, do it outside or in the garage.

RCA

Serious question, do you really need to clean an AR barrel if it’s not a precision rifle?



ETA: TL:DW rifle has well over 10k rounds through it and the barrel has never been cleaned. He cleans the barrel contaminants (copper/lead/etc fouling) 1 by 1 to see if accuracy changes. It doesn’t.  

He says Do Not remove copper from your barrel.

P.S. he has a chemistry degree.