It's copper fouling.

 

Copper brush, a little Hoppe's No.9, a few patches, and you are good to go. No big deal.

 

Normal.

 

Thanks much for the answers, guys. I was worried about rust.

 

Thanks musch for the answers, guys. I was worried it is rust.

Swab it with a real wet patch of Hoppe's 9 and get the bore good and wet. Let the barrel sit for 10 minutes or so, then wipe with tight dry patch. You should see the green streaks which are the dissolved copper. Repeat as needed and using a brush will help speed things up a bit, but a copper brush will also dissolve a little bit with Hoppe's 9.

 

Thanks for the tip!

 

The Hoppe's product that I have found effective for bore copper removal is Hoppe's BENCH REST 9 Copper Solvent, which is a totally different product from plain common LGS Hoppe's No. 9 solvent.

https://www.hoppes.com/traditional/bench-rest-9-copper-solvent

Hoppe's also make a higher grade copper solvent:

https://www.hoppes.com/black/hoppe-s-black-copper-cleaner

I've never tried that.

I find plain No.9 solvent to be a very ineffective copper solvent.

Also, use a BRASS brush (not COPPER). The nylon brush that Glock includes is just for show. It's little better than nothing.

Finally, what your barrel shows now is of absolutely no concern. You could fire another thousand rounds and not see any difference. So...don't get too hung up on seeing those deposits.

 

Finally, what your barrel shows now is of absolutely no concern.

Thanks for the answer, mate

 

Finally, what your barrel shows now is of absolutely no concern. You could fire another thousand rounds and not see any difference. So...don't get too hung up on seeing those deposits.

Since the copper fouling is mainly cosmetic and has little effect on your barrel and its functioning, you could just skip the copper solvent altogether and save yourself some time and money.

If the cosmetic appearance of your barrel is important to you, then go ahead and try a copper solvent like the one Mike-M uses.

 

Yep. I haven't used solvent in years.

 

If the cosmetic appearance of your barrel is important to you, then go ahead and try a copper solvent like the one Mike-M uses.

I use copper solvent, but in 24 years of Glock ownership I've never used it on a Glock. It's possible it may be on rare occasion appropriate for the new more complex Glock Marking Barrel rifling of post-Gen4 barrels, but I own none of those.

I use copper solvent primarily on old military surplus rifle and pistol barrels...and what comes out of a century-old Mauser that has not been completely bore cleaned in 80 years can be quite impressive. But this experience does not serve much to apply for Glock pistol barrels.

 

Do you have any information on whether the copper fouling has any effect on the newer Glock Marking Barrels?

I wouldn’t think so, but it would be interesting if it did.

 

Do you have any information on whether the copper fouling has any effect on the newer Glock Marking Barrels?

No, I'll just watch other people's experience and reports over the next few years.

 

...
Is it normal?
Is it rust or copper fouling?
Would this affect function at all or just simply cosmetic?

P.S. For cleaning I use nylon brush comes with Glock box. I also use Ballistol Oil with Hoppes 9 bore cleaner.
... .

I echo what others already told you.
It’s normal.
It’s only copper fouling.
It will not affect the gun’s function at all because it is only cosmetic.

Glock nylon brush is very ineffective to say the least. Bronze or brass bore brush is recommended. I use Brownnells Double Tuff Bore Brush (https://www.brownells.com/gun-clean...amp-bore-snakes/bore-brushes/special-line-double-tuff-bore-brush-prod25919.aspx) and Hoppes No. 9 to clean my Glocks every 1K rounds or so. In my experience, they are the best bore brush I have ever used.

 

If the cosmetic appearance of your barrel is important to you, then go ahead and try a copper solvent like the one Mike-M uses.

I'll pass I don't really care about cosmetic perfection inside my barrel, just wanted to be sure it's a copper fouling and not rust.

Glock nylon brush is very ineffective to say the least.Bronze or brass bore brush is recommended.

Sure, I'll use bronze or brass instead of nylon. And thanks for the "echo"!

 

I use Seal 1 on my Glocks and this product is specifically for the bore!
My Glock barrels no matter what gen looks like new!