It may be a sharp edge on the bolt lug that pushes the rounds out of the magazine, or possibly a burr on the outside of the firing pin hole on the face of the bolt (perhaps caused by dry-firing?). You can check to see if it is happening during chambering vs firing by chambering a live round (on the range, please, not in the house/apt), and then carefully extracting and ejecting the live/unfired cartridge and inspecting it for the damage you are seeing on the fired rounds.
"Placement is power" -- seen in an article by Stephen A. Camp
(RIP, Mr. Camp; you will be remembered, and missed)