Witness marks in upper from BCG cam pin

[danpass]

Is this typical?

I just noticed so I checked my RRA NMA2 that I've fired 10x as many rounds thru and it is there as well though much less obvious.

About 200 rounds

[Servo]

Yes it's completely normal.

[danpass]

Hmmm …… well ok.

I just wonder why have this cutout in the upper for the cam pin if it is going to strike anyway ……

Cutout centered too far forward?

[Blak1508]

It's settling in. Getting comfy.

[Iraqgunz]

What is your experience level with the AR15 FOW?

[danpass]

Just this and my A2. Self researched.

This one I built.

(As far as lube, I had wiped the area to get a better pic)

I had gone thru your single post on Inspection

[steyrman13]

Is this typical?

I just noticed so I checked my RRA NMA2 that I've fired 10x as many rounds thru and it is there as well though much less obvious.

About 200 rounds

Is that a crack in the upper? Right passed the marks you are concerned with?

[Safetyhit]

Is that a crack in the upper? Right passed the marks you are concerned with?

That's the bolt carrier and I was just wondering the same thing based upon the third picture down.

[steyrman13]

That's the bolt carrier and I was just wondering the same thing based upon the third picture down.

Ahh small phone, small pics. Look in first pic too though

[ASH556]

Just a thought here and perhaps someone with more knowledge like IG will respond:

Your 20" A2 RRA has a rifle length gas system, which will yield a smoother and slower-operating bolt. The BCM carbine bold is operating more quickly and violently. I'd wager that has something to do with the wear difference you're seeing.