What am I seeing?

[BBQJOE]

This is the BBL of my new S&W M&P9mm.
I have shot probably 200 rounds of cast through it. Maybe a little more. I had some leading problems. I read here about the choreboy. (made sure they were copper, not copper coated).
I worked on it quite awhile. Then gave it a toothpaste polish.
In this pic you can see something going on in the grooves. I guess I've never looked this closely at a barrel, or anything else for that matter since I got into casting.
Are these lines normal, or is it leading? Are these just machining marks? Am I over analyzing this whole thing?
These pics will enlargen when clicking.
69004

69005

[Jaak]

That is one clean barrel. Looks perfectly fine to me, but I am just starting out myself.

[BBQJOE]

BBQJOE,

Are what you are asking about are the longitudianal striations located in the grooves? If so, these appear to be normal tool marks left during the rifling process and are nothing to worry about.

PB
Yes. Thank you. I was beginning to think I had permanently lead streaked the BBL or something. Whew!

[Hamish]

The Paper Patch guy's will tell you that your barrel desperately needs polished by paper patching. But then, they try to convince everyone into their particular brand of madness,,,,,,,

[BBQJOE]

I suppose then that these tool marks are the "Unique" signature making marks that are used in ballistics forensics.

[44man]

That barrel looks just super clean to me. I see shadows and the smoothest tool marks ever.

[runfiverun]

a 6-800 grit type finish is just dandy in a barrel.
keep on shooting it, it will polish out even more on it's own.
antimonial alloy will help it along some, then put down a grey wash maybe, it depends on the lube.

[jonp]

Looks like a good barrel to me. I'm not sure I'd spend a great deal of time going after it anymore unless you want to.

[MtGun44]

Very clean barrel. Those are cutter marks from cutting the grooves when
rifling the barrel.

Bill

[BBQJOE]

Thanks everybody. I tell ya, it was a hard pic to get.

[I'll Make Mine]

Thanks everybody. I tell ya, it was a hard pic to get.

Worth the effort, though -- that's one of the best photos of rifling (very, very clean rifling!) I've seen. As noted above, those are tool marks, and yes, they're what leave the distinctive marks on a bullet that can be used to match a bullet (say, found at a crime scene) with the gun that fired it.