Got to thinking about how easy to pick the best cleaning routine if only the rifling was on the outside. Then thought of a screw. So deposited some copper from copper wire in the threads of a steel screw. Mostly by twisting a loop around the threads, holding it tight with pliers and screwing it back and forth. Also some scrubbing back and forth with a short piece of wire and considerable pressure. This eventually got me a nice even streak of copper looking very much like copper deposits in the muzzle end when viewed with a bore light.

Now viewed with a 10x loupe, the surface of the screw was quite rough. Hopefully no one's bore is this rough. But it took a pretty even looking copper coat. Decided to try 3 methods of cleaning. Solvent only, brass brush and solvent, and RemClean abrasive. Tried to keep it as close to barrel cleaning as possible. Cleaning patch soaked with solvent pinched between fingers as the screw was turned through. Brushed along the axis of the threads, meaning almost perpendicular to the screw.

Well using only solvent it was possible to get it completely clean. But when partly clean, there were uneven splotches of copper all along the threads. And this a couple of patches after any green or blue residue was left on the patch. Still could see splotches of copper in the dips and rough pores of the threads. Clumps of it in deeper pits really.

Now using a brass brush, it was surprising how it would smooth out the finish of the copper coat in just a few strokes. It has very fine lines the size of the bristles. But this seemed to spread it out from those clumped splotches. Then when going to solvent. The copper seemed more evently coated, and came off almost in layers. After no more discolored patches of solvent the remaining copper was in long thin spread out streaks. As if the brushing had spread it. There was none of the clumpy splotches in threads. Only whisker thin streaks here and there. It also took fewer swipes with the solvent soaked patches to completely remove the copper.

Using RemClean, I never fully got the threads clean. I think it wasn't a fair test as the patch with the RemClean on it couldn't really get into the threads to allow such a fine abrasive to work. At least not in this manner. Used on a jag inside shallow rifle grooves it probably is much more effective.

I used Hoppes #9, then repeated the test with Shooter's Choice. Results were about the same. The Shooter's Choice did get all the copper much quicker than the Hoppes as you would expect. But the effect with the brush seaming to burnish the copper coat and let it clean off quicker and more evenly was apparent. Actually a brushing followed by one patch of Shooter's Choice got nearly all of it.

Also tried a home-made Outer's Foul Out arrangement. 12 volts through a vinegar and household ammonia solution. This too cleaned all the copper quite thoroughly. But even it, if stopped partway left clumps that a brushing would have evened out. I would think a brushing before Foul Out cleaning would also be useful.

Also, after brushing etc. when clear of copper, I saw no effect on the surface of the threads. But this was only a few strokes, with abrasive or brush. Didn't expect to see any.

Would like to have also tried a nylon brush. But all this fiddling to coat the threads with copper was quite tedious.
So called it good enough.

Would seem to me, especially during break-in, that the burnishing, evening out effect of the brass brush will aid in smooth seasoning of the bore. And help it break in to a much smoother more even, more easily cleaned barrel finish. I also see no reason much the same wouldn't be true of lead bullets. But I didn't care to handle little bits of rubbed off lead to try it out this way.

Anyway, would invite, comments, criticisms, point out of errors etc. I know rubbing copper on like this isn't quite the same as the speed, and pressure it gets put in rifling. Though I got it to have the same visual appearance. But fire away, interested in what ideas others may have about this.

I agree 100% with the validity and conclusions from your experiment.

The instructions for Rem Clean call for the patch to be on a brush.

Interesting experiment. Thanks for sharing it!

I am sure the solvent wasn't redepositing the copper on the screw. For the reasons you explain, I used the brush dry. Sorry, should have mentioned that.

Certainly wouldn't do that in real cleaning. A patch to clear out any powder residue etc. would be used first. I actually would like to do it both ways. And I definitely wanted to try a nylon brush. But it was a rainy day experiment, and my poor fingers got all tired out.

Would the bristle's of the brush, lubed by solvent work less well? Good question, I don't think they would, if anything the solvent might soften the copper to make the brush work even better. But I can only guess, trying it both ways might have answered that question.

Well must have been a good experiment. Good ones usually raise more questions than they answer.