Had a similar experience with US Repeating Arms Co (Winchester) about 20yrs ago only I went through a local Winchester authorized repair center. New rifle and spent brass had well defined concentric rings on the shoulder. He sent rifle and spent cases to manufacturer for warranty work. Rifle returned with no paperwork, no indication of what was done and no spent brass to show repair. Don't know if they polished chamber, recut and set barrel back, or replaced the barrel but when fired there were no rings on the brass.
Bookmarks