Never seen this before

[Reloading Guy]

This is improperly installed primer, and nothing more I think. Just check when you take your loads from tray to box, or place each round face down in box so you can see all primers. That will stop this largely.

 

[divingin]

I had a guy give me about 500 rds of some 5.56 stamped brass before I remember the head stamp as some sort of crosshair with a circle around it thing and the 5.56

The circle and cross is the NATO identifier (meaning the ammo as loaded was to NATO specs.) The manufacturer will usually be a 3-letter ID code.