Just came home from a range session with a new (to me) CZ 550. The gun shot fantastic. I gave it a very thorough cleaning when I got home, using copper solvent. Scrubbed with a brush and patched until no more blue. It’s clean! But when I look into the muzzle end of the bore I see copper colored rifling. I wish I could figure out how to post a pic here. Anyone seen this before? Any concern? The bore is bright and shiny, no rust, no pitting. The coloration appears to be in the recesses of the rifling.

I think it would be some remaining copper fouling - try a couple more patches with copper solvent.

Did that a few dozen times! The patches come out like brand new. No blue at all!

Run a patch saturated to dripping with the copper solvent, keep it out the magazine and trigger group, let it sit for awhile and then see what you get on a well fitting dry patch.

Or spray some wipe-out foam down your barrel (from the breech end) and let it sit for a few hours. I shoot a bunch of Barnes TTSX bullets so I deal with copper fouling a lot, if any copper fouling is in there it wont be when your done 👍......Hb

Many of the liquid copper bore cleaners won't remove copper as well as people are led to believe. JB bore cleaner will absolutely remove stubborn copper fouling.

Did you clean it before you shot it?

You may want to see if it doesn't really need a lot of cleaning to keep shooting well.

If it's clean and shoots well, I'd find something else to worry about. Next time you shoot it, even if it's clean down to the atomic particle level, guess what happens the first time you light it off?

If the gun shoots good then leave it alone. Lots of good guns have been ruined from too much poor cleaning. If it ain't broke , don't fix it.

If it shoots well I wouldn't worry about it. I would see if the first shot zero will be close enough with an almost dry bore. Lubed then dry patched. This is only for peace of mind that condensation or corrosion doesn't occur under the copper while hunting. I would also explore loads with a de-copper agent added. Most of the newer powders have this. I have not tried it but David Tubb's has a de-coppering agent you can add to any powder, it has some cutesy name like Tubb Dust or something similar.

A too clean/smooth barrel can actually increase copper deposits. If this is a likely factor you can either run some 220 grit valve grinding compound down the bore on a tight patch or a pass with a stainless steel brush will add some longitudinal scratches to the bore. With either only go from breech to muzzle and remove at the muzzle and replace for the next pass. Three to five passes should be enough.

Wipe Out.

would it potentially harm the bore/rifling to just leave the copper in there? i mean could the copper trap moisture under it and rust the barrel if you don't clean it to bare metal? i've wondered this for awhile personally. i've always been a little leery about leaving a fouled bore for too long for fear of rust/pitting.
Big Ed

Two excellent suggestions. I have also treated it with the foam, then hit it with the JB after the foam has loosened it up and it comes clean. Helps with carbon, too.

Just had this same problem with a Ruger 77 I recently picked up. I scrubbed and scrubbed and let it soak with wipeout. The only thing that I found that cut the copper was sweets 7.62.

Was it heavy buildup, or a copper "wash" over the steel? Would it still shoot well with some copper in it?

Gun shoots great.

I did use Gunslick brand foaming bore cleaner and let it set for 30 min. Then brushed thoroughly, then patched wet and dry alternating Outers Nitro bore solevent until no more blue. Those products were just what I had on hand. All said on the bottle they remove copper fouling. Yet still a visual inspection looks like copper in the rifling.

That stuff/process inadequate? I did order some Barnes CR10, hopefully that works better.

Try and see if it doesn't need that much cleaning all the time. I have worked with several rifles that shot well with some copper color in the bore. Every now and then I pushed through a Ballistol laden patch followed by a couple of dry ones to keep powder fouling down a bit.

This is 100% correct. While I don't know why, solvents won't such some copper fouling. JB Bore Paste works every time...and quickly.

Can one of you guys post a link to the JB bore cleaner that is good with copper? I see several different types. Which one are we talking about and what is the best process to use?

Please explain copper “wash”?

If you are applying a copper solvent, and then brushing with a phosphor bronze brush, you may in fact be dissolving the brush.

I haven't used the Gunslick product, because I find Sweets 7.62 does a sterling job on copper fouling.I also don't understand why you'd use the copper solvent first, then the nitro solvent.

Here's how I do it:

I start with a nitro solvent (Hoppes No 9). I apply it on a loose patch on a loop, and then give the bore a good going over with a phosphor bronze brush, letting the brush go all the way out of the muzzle before reversing direction. I then patch out using a jag, until the patches come out clean. I repeat the process if necessary, until there's no powder fouling on the patches.

I then have a good look at the bore from each end, to judge as to whether I need to worry about metal fouling.If I do, I again put a fairly loose patch on a loop. I wet this well with Sweets 7.62, and pump it up and down the bore vigorously - getting a bit of a foam happening seems to make it work better. I then patch out using tight patches on a jag until the patches are clean, and have another look. If there still seems to be copper I might repeat the Sweets, but let it sit for a while before patching out again.

Once the bore seems clean I put a lightly oiled patch through and call it done.

Others may have different techniques, but that has worked for me for decades.

I still use Shooters Choice for copper fouling and JB Bore Paste for stubborn build up of lead and copper and it works fine for me. Wipe out is a last resort for me because of the mess it tends to make, but it can be a good step in the process...

I only used the copper foaming solvent first out of laziness. Hoping it would do most of the work for me.

Regular. JB bore paste in the plastic jar. I mix mine with a little Kroil, wrap a patch around a bronze bore brush so that it fits tightly in the bore, soak the patch in the JB/Kroil mixture, and force the patch through the barrel. Normally my barrels are clean in 20 strokes or less. Make sure the patch/brush fits tightly and clean out the mixture when you’re done.

That being said, the only time I clean a barrel to this extent is when I apply Dyna Bore Kote, or buy a used rifle that has a ton of fouling in it. Cleaning this much normally changes groups in my rifles, sometimes for the worse. It may take a bunch of rounds to get the barrel back to shooting consistently depending on the barrel, which is why I normally don’t worry much about a little copper in the barrel, as long as the rifle is grouping okay.

It's awkward to explain, looks more like coloration rather than a material buildup.

That’s precisely what this looks like.

Leave it alone! Several have already mentioned this, it is best to leave the bore alone. You said it shoots great, so be happy and leave it alone. I had a friend that shot more ammunition just fire forming cases than most of these people on the Campfire do shooting. You have no idea how much this guy shot. He was also a surgeon and couldn't abide by any residue left in the bore.

He finally bought an electronic bore cleaner that you seal the chamber, pour in a solvent then put the electric rod into the bore and let it sit for hours. It did pull all the copper out of the bore, but he never shot enough ammo through that gun to get it shooting as well as it did before the treatment.

Keep that gun with the bore it has and shoot it...

Then if the accuracy doesn't fall off I wouldn't worry much about it.

I have a rifle that does its best when fouled a bit. It has a cro-mo barrel so I give it a couple of Ballistol laden patches now and then since it's pretty moist here in Cajun country. (My shooting range used to be a rice field. When I mow my back yard I watch to avoid cypress knees coming up through the grass. )

This is good advice. You said it shoots good so don't worry about it. Now when you go to shoot the rifle again after all the cleaning the first several shots are going to be laying back down a base of copper. Some copper fouling in your barrel is good if its covering up tiny little imperfections in your barrel and aids in a consistent bore. Towards the end of the muzzle pressure and heat is dropping and most barrels will show more copper in that area. Unless it starts grouping poorly don't remove the copper if your concerned about moisture just run a patch lightly oiled down your barrel when your finished shooting.