Guys, appreciate the information. The barrel is marked 7 R M, so I assume it is a 7 Remington Mag. I fired only one round through the rifle. There are scratches on the fired brass. Am not sure, since I only fired one round, and that has been 3 weeks ago, whether the extractor was engaging the brass or not. I removed the brass with a cleaning rod. I realize that to rechamber, barrel would have to be set back. Am partial to the 280 cal. and if the chamber is boogered up in any way, that would be the logical thing to do. Unless there there are any other ideas?