View Full Version : What is copper fouling?

January 6, 2000, 05:39 PM
I have read a lot about barrel break in and fouling. The general message seems to be that a patch or brush be run through the barrel after each shot until there is "little indication of copper fouling". What is an indication of copper fouling? Should the patches come out perfectly clean?

January 6, 2000, 10:12 PM
Yes the patches should come out perfectly clean.

Copper fouling is residue from the bullet jacket material (usually not pure copper) which is left in the bore after firing. If you use a cleaning solvent that is designed to remove copper (as opposed to lead) the patches will show black color initially and show a slight blue/green color as the copper is dissolved.


January 10, 2000, 12:26 AM
There are opinions both ways on whether the break-in does any good for a new barrel or not. I've done it on all 3 of my custom stainless steel barrels on AR15 match & service rifles. I use Shooter's Choice solvent to get powder fouling out and begin to dissolve copper fouling, followed by RemClean, an abrasive cleaner, to finish. After another patch wet with SC, I dry patch, then fire another round. After 5 single shots, I went to 3-shot groups for another 9 rounds. I then shot several 5-shot groups, cleaning completely after another 20 rounds. After that, I cleaned the bore completely after every 20 rounds a couple more times. Now, using moly'd bullets exclusively, I clean with two wet patches, then dry patch and oil. Every 300 rounds, I go in with RemClean again. My Douglas barreled Service Rifle has nearly 4600 rounds through it, and is starting to get rough enough to copper foul even with moly'd bullets. It still shoots good enough to clean the 200 & 300 rapid fire targets in a High Power match, but I'm beginning to doubt it's ability to hold the 10-ring at 600yds.

I guess what it boils down to is whether you believe all this helps or not. I'm sure it won't do much if anything for a chrome-lined barrel, such as the military M16 has, but it's worth the time and effort to me to get the most out of an expensive custom match barrel. If done correctly, with a rod guide to prevent damage to the chamber throat, I don't see what it can hurt.

January 10, 2000, 10:28 AM
Barrel Break In - Mystery or Myth? According to Gale McMillian, myth. Do a search on "Barrel Break In" on the AR15 websight ( http://forums.ar15.com/cgi/Ultimate.cgi?action=intro ) and you'll see quite a few posts over the last 100 days. Armalite has something about barrel break in on their web site under Technical notes. ( www.armalite.com (http://www.armalite.com) )

I'll second Flatlanders recommendations about stainless steel barrel break-in. I spent eight hours (over this past Saturday and Sunday) breaking in a new Armalite National Match service rifle.

I used Shooter's Choice Copper Solvent to get the copper out of the barrel. You have to let it work a while (10-15 minutes) so the ammonia will chemically combine with the copper. The result is a blue-green sludge that has to be cleaned out of the barrel with several more "wet" patches of your normal cleaning agent. When you get a clean patch, you can then dry patch and shoot the next segment of the barrel break-in (and then the cycle starts all over again).

I was also shooting moly bullets and was done in about half the amount of ammunition that non-moly would have taken. The copper fouling quit after about 20 rounds. The time consumption was due to other things going on at the range (Service Rifle practice match and open shooting). Spent 99% of the time cleaning and 1% actually shooting / sighting in the rifle.

For chrome lined barrels, the word from experienced shooters is "fire 200-300 rounds to polish the chrome". Totally different from stainless or molychrome barrels.


[This message has been edited by DblTap (edited January 10, 2000).]

James K
January 10, 2000, 12:28 PM
Rifles are rarely plated, but note that any solvent that attacks copper can also damage nickel plating, which usually has a copper underlayer. The solvent won't affect the nickel itself, but will dissolve the copper if it can get to it.


January 10, 2000, 02:07 PM
What I have heard to do to rid the barrel of fouling is to coat the inside of the barrel with a copper removing solvent of some sort, then sit the rifle on its muzzle resting it on a clean, padded, white cloth. Let it soak and drip over night, and in the morning check the cloth for the blue-green colour. if it is there, then wipe the barrel clean of the solvent, and keep doing that until the patches come out clean.