Muzzle brake: marks where bullet exits brake

[ronas]

Muzzle brake is factory Sako on TRG-22.

I noticed marks on the <span style="font-weight: bold">bottom </span>of brake where bullet exits. What might be causing this?

I know accuracy is not affected since I shot a 10 shot group with moa of .1" over 1/2" moa at 100 yards. That was with 155.5 bergers loaded with 47.5 gr of varget.

The only thing new since I got the marks is I'm trying out some BIB bullets that are 155 gr. with FB also with 47.5 gr of varget. I've only shot 3 shot groups since I was figuring out what was best seating depth for smallest group. Well I figured that out and I shot
two 3 shot groups both 3/8" MOA

What might be causing the marks circle in red in the photo below?

<span style="font-weight: bold">Edited:</span>
I was able to clean what I thought were marks off with butches bore shine and one of those copper colored bore brushes. I must have been lead. So question is are one or the other of the bullets I'm using disinterating on exit from the muzzle brake? If so it seems odd accuracy is so good.

 

[rfb]

Re: Muzzle brake: marks where bullet exits brake

I'm going to pull an unscientific answer out of me arse and say lead, copper, and carbon fouling got deposited by hot gases exiting the brake.

Are there similar marks on the "vents" of the brake?

 

[el gordo2]

Re: Muzzle brake: marks where bullet exits brake

As long as it's not affecting you accuracy I wouldnt worry about it.


I had a problem with my 338LM brake when the screw was over torqued with the clamp. The brake would become misalighned and the bullets would strike the baffle and cause huge POI shifts. I learned to only snug the brake down from there on out and havent had a problem since.

You can see the copper splash on the baffle.

Notice the copper mark on the exit hole.