A friend finally got to shoot his new rifle today. While boresighting, I noticed a bunch of crud. He had not cleaned it.

I ran a few oil and dry patches through til the black/tan faded.

After 10 shots I ran a brush and patches with Hoppe's #9 through. They came out rather dark, but almost seemed to have a blue tint. Not turquoise or green, blue.

Is this just some remnants of the nitride process mixed with copper fouling? Normal?

The blue is a reaction from the ammonia in the solvent. Could be copper fouling from the bullet, or could be a false positive if your bore brush or jag is made of brass.

Anyone else?

What he said.

Reworded: Has anyone else had dark blue patches when cleaning a new nitrided barrel?

Did you clean the bore before you shot it? Could be residual oil in conjunction with the copper.

I hope you cleaned that barrel before shooting it if it wasnt a factory barrel. Nitriding leaves a lot of fouling in the bore due to the process. You really gotta scrub that stuff out.

The blue may be i mixture of copper and the nitride residue coming out of the bore. My nitrided barrels copper fairly badly until they fire polish, and then i get very little copper fouling in the bore.

Scrub it with a stainless brush and foaming cleaner until all that black crud comes out. Stainless wont hurt a nitride bore as long as you use it just enough to get the fouling out.