Weird marks on spent 5.56 casings

[NicoDiko]

Hi guys So, i got a new barrel on a Ruger american 5.56. Headspace should be fine. It makes these weird powder burn marks on the spent casings around the neck/shoulder area. I havent seen something like that before. Do you guys know whats going on? The ammo is Sellior/bellot 223 factory fmj loads.

Best regards, Nico

 

[Dogtown]

Fluted chamber?

 

[Tiger_Shilone]

Looks like HK brass from the 91/93 roller series or Larue’s “Xtraction” chamber in their AR‘s.

 

[NicoDiko]

*double post

 

[NicoDiko]

Fluted chamber?

I dont think the chamber is fluted. Nothing that i can see with the naked eye in any case. Is it possible that it could be a headspace problem? i did not replace the barrel myself, but, headspace should be OK i was told.

 

[918v]

Run your fingernail over the black carbon streaks to see.

 

[NicoDiko]

Run your fingernail over the black carbon streaks to see.

Thx, there is nothing to feel

 

[Doom]

first thing I would do is clean that rifle and then shoot differs ammo.

 

[msgriff]

If your barrel came from Ruger, it might be a CHF chamber along with the rifling, and those might be caused from the mandrel.

 

[DHDeal]

A bore scope will tell the tale most quickly. As others suggested, clean it making sure to get the chamber and try it again. Maybe I should ask if the chamber was clean before those shots, was the rifle brand new, do you have different ammunition, and do you have a bore scope to look inside?

 

[pmclaine]

Long, loose throat.

Your getting some carbon evidence up to the point the brass has sealed the chamber.

Maybe hard necks in that ammo that are not expanding under pressure.

More important how does it shoot?

If it shoots great consider it your rifle marking your bras specific to you for recovery.

 

[NicoDiko]

Hi again guys. I got a borescope. The barrel indeed seems to have some fluting in that area. it shoots fine, so i just leave it at that. thx for alle the replys

 

[DHDeal]

Glad it is going to work out for you. You needed the borescope anyway. I like to use mine to freak myself out looking down the barrel (just joking)....