Marks on fired brass

[jbonnette]

I fired some test shots from a new 300blk gun that I built. After inspecting the brass, I noticed some identical marks on them. Any idea what might be causing these marks? Anything to worry about?

 

[Barney88PDC]

Marks on the body look like they are coming from the feed ramp when the round is being loaded. On the neck I am not so sure but I would say during extraction / ejection. Possibly hitting the locking lug or ejection port on the way out. Semi-autos are hard on brass and hence you usually have to toss the brass long before you would out of a bolt gun. I noticed my 300 BLK slightly bends the necks in on ejection and I defenately have some marks on the brass deflector. Nothing a die does not fix during resizing though. Loaded'em up and Choot.

 

[twokids]

If your brass lands behind you the marks on the first picture on the body of the case are probably the brass deflector.

 

[Akajun]

I immagine that your gun is an ar, and that those marks are from the barrel extention. Look at your bolt, see the square lugs? you have the reverse of that on the barrel extension. The two top marks are spaced that distance apart.

You can try clipping a coil or two off the extractor spring and see if that helps.

 

[jgreco15]

I noticed my 300 BLK slightly bends the necks in on ejection and I defenately have some marks on the brass deflector. Nothing a die does not fix during resizing though. Loaded'em up and Choot.

I have noticed the same on my BLK.