Copper fouling

[jdmstuff]

I'm currently shooting through a batch of Hornaday 55gr FMJBT bullets that I reload over 24gr of Benchmark and have noticed copper fouling at the end of the barrel and on the compensator. I've shot about 300 rounds through this gun and have not really cleaned it. I pulled it out of the safe tonight and found this. The cases look fine and there are no signs of excessive pressure. The picture below looks like wear, but is actually green/blue in color. I also have another gun with a stainless barrel that has shot through the same amount of rounds, but the fouling is even worse on that one. I don't have any pics of that gun as I just sent it in for service. Could this be caused by unburnt powder or something else? It seems that it only occurs on my piston guns. I've shot the same reloads through my DI rifles and they don't have any fouling whatsoever.

[ZER0_]

Like you said, it sounds like oxidized copper (copper fouling) to me. It makes even more sense that it developed if you haven't really cleaned it.

Looks like you need to get yourself a copper cleaner solvent. I've heard good things about 7.62 sweets.

A google search brings up others with the same problem.

[madjack956]

Sweets will do the trick if its indeed copper.

[jdmstuff]

I can deal with the cleaning, but I've never noticed it on any of my other guns. I just thought there may be something wrong with my reloads.

[DSMeyer]

It's copper alright, nature of tre beast when shooting copper jacketed bullets. Just wait til you shoot non lead hunting beasties. You can use boar tech or M pro7 the do the initial cleaning and sweets to really get the rest out. If that doesn't do the trick an outers foul out rod will remove all of the copper from the nooks n crannies. I have a half dozen rifles that just love to strip copper, it's a good 2 hours of cleaning to get them back to my likings.
The other thing is it would be a good idea of checking the storage humidity. If your promoting copper oxidization quickly then your also promoting other types if oxidizing.

[jameshenry]

Once you get em clean it will usually be easier to keep them clean. I always clean my guns after shooting them, within 1 week anyway.

[Yoteman]

I de copper at about 50 rds in my varmint guns.
The newer foam products are safer and clinge better than the older traditional products. Gunslick and others make great foam copper getters!
I use this one!

[Enfield47]

I'm curious to know why it's only on the piston ARs and not the others. I've never seen anything like that before on my direct impingement ARs shooting the same bullet and powder as the OP.

[DSMeyer]

I'm curious to know why it's only on the piston ARs and not the others. I've never seen anything like that before on my direct impingement ARs shooting the same bullet and powder as the OP.

A lot of it depends on many factors. The barrels rifling, a rougher barrel wil strip more copper naturally. Different powders and primers have different reactions to the copper. Type of cartridge is a huge factor, the faster a bullet is pushe the more friction and heat is generated, the more copper is transferred.
I have bolt guns that copper, di semi auto as well as piston driven semi's that copper. Some foul out faster than others, but they've all had copper fouling.
Most of the time I have had the nice green growth was when I got lazy and didn't clean the rifle after shooting it. This usually was after a month.

[jdmstuff]

Thanks for the tip on sweet's. I picked up a bottle today and will give it a try in the morning.

I'm still curious as to why the fouling is more pronounced on my piston AR's as opposed to my DI ones.

[Southpaw45]

Sweets 7.62 is good stong ammonia based stuff. It stinks bad and will etch the bore if it dwells to long. I would like to recommend Bore Tech Eliminator. Is lifts copper fouling fast like Sweets but smells much better and wont damage the bore if you let is soak awhile.

https://www.boretech.com/products/eliminator.shtml

http://www.youtube.com/watch?v=VjO8O-9jXRs

[Southpaw45]

Thanks for the tip on sweet's. I picked up a bottle today and will give it a try in the morning.

I'm still curious as to why the fouling is more pronounced on my piston AR's as opposed to my DI ones.

Rememer not to use any kind of brass or bronze brushes or jags with this stuff. It will give false positive readings for copper fouling. Use aluminum, plastic or special alloy jags and nylon brushes with an aluminum winding. It could be the condition of the bore. Bores that are more precised manufacured and are hand lapped or polygonal bores will have less fouling and stay cleaner longer. Also proper barrel brake in is a must with less expensive mass produced made barrels.

[Witch Hunter]

After you get the copper out, try some JB bore paste it seems to smooth out a rough bore. Oh, and don't let Sweets sit in your bore too long. It is a very strong ammonia bases cleaner. I use Hoppe's overnight to soak out a bore,.

[jdmstuff]

Thanks for the tips!