Copper Fouling in Marlin .30-30

[GunAdmirer]

I have a pawn shop rescued Marlin .30-30 with micro-groove rifling. I bought it because it looked new and the price was unbelievable. The bore was pristine. It hadn't been shot more than a few times.

I shot it 6 times with Winchester brand ammo this afternoon at range. When cleaning I noticed a good deal of copper streaks in the rifling near the muzzle. Is this normal in rifles? Is this normal for a Marlin with "micro-groove" rifling?

I didn't expect that much copper fouling since the .30-30 is a relatively low velocity round.

 

[dakotasin]

yes, normal. yes, it is normal for microgroove - or any groove for that matter. wouldn't worry about it until accuracy falls off, then a little barnes cr-10 will get 'er patched right up.

 

[Firehand]

Depends on the bore, some may be a fraction 'rougher' than others and foul faster.

It's not something I use frequently, but you might try giving it a thorough cleaning with a good copper solvent like Sweet's, then polishing it with JB Bore Polish, then see if that helps out.

And be sure and use a muzzle guide to protect the crown if you do. And for normal cleaning, for that matter.

 

[Z_Infidel]

Heck, I've even seen this with a revolver and jacketed bullets. Blue Wonder also works well on removing the copper.

 

[mainmech48]

It may well be endemic to Microgroove barrels. I have an older Marlin 336 in .35 Remington that also shows signs of copper fouling after a few rounds. Doesn't seem to affect the accuracy, though it's really hard to tell for sure when a typical session at the range consists of strings of twenty or fewer rounds of any given load. Especially as I routinely clean the bore in between strings when I'm doing load development.

To be fair, getting it out has never been much of an issue anyway. Generally, I don't even have to brush on copper in it, as even the most prosaic solvents like Hoppe's No. 9 seem to get it out without resorting to scrubbing. Non-gaschecked lead bullets are worse, even at "rimfire" (c. 1200 f/s) velocities, varying to a considerable degree with the powder being used and the alloy. Even then, a few passes with a brush and solvent, an hour's soak, and a couple of dry patches generally do the trick.

FWIW, my M-39M .22 also has Microgroove, and doen't seem to collect any metal to speak of, even when several hundred rounds go through it in an afternoon. Go figure. IMO, a lot of this may well be more a factor of bullet lube system and composition than anything else.

The most hassle-free way to remove gilding metal fouling from anything that I've found are the new "foaming" and gel solvents. They're amazing. One application following the package directions and you're done. I did some experiments on barrels that showed clean patches after using my former routine. Outer's Foaming and Blue Wonder gel both got me "green" patches where I would've sworn no copper was left.

Now that this's got me thinking about it, I'll have to dig out the 336 and see if I get any out of it with them.

 

[Werewolf]

Copper fouling in a rifle barrel is normal. What isn't normal, if indeed you are experiencing copper fouling, is that the fouling only occurs near the muzzle. Various conditions can cause this. What caused it in one of my revolvers was a land that was just a bit higher than the others - in other words the land diameter actually narrowed a bit at the muzzle and that land tended to collect copper - weird huh. Gunsmith fixed it - no more copper fouling.

I'm going to assume you use a borelight. You know those colored filters that come with one - they do have a use.

Put the green one on the light and make sure you've got fresh batteries. Then shine the light into the chamber end of the barrel. You shouldn't see any dark streaks - the bore ought to be all the same - dark streaks are copper.

You can see this better if you shine the light into the muzzle where you're seeing copper. The copper will be darker than the rest of the bore.

Note - not all green filters are the same. You really need one that is a true monochromatic and to be honest you can't really tell whether what comes with the bore light is monochromatic or not. Photography shops sell gel fitlers of different colors - some of which are monochromatic. Cheap - just cut to size.