Got a S&W M&P in today with a live round jammed in the chamber. Took it out back and mortar'd it out on a wood board. Round was bent in the middle with a nice brass shaving on one side. Chamber inspection revealed a knife edge on the chamber mouth. As the round fed up it dug into the edge and got bent as the full force of the bolt hit it. Of course the fix is to chamfer the chamber mouth(as it should have been at the factory). Well I didn't have a dang reamer or even a countersink to do the job. My solution was to use a 1/4 inch drive socket on the end of an extension to swage it. The smaller sockets have a nice radius as the bit tapers. I selected one that just fit inside the chamber and tapped it mildly with my bench hammer as I rotated it. Rolled the edge over beautifully and ran 30 rounds through it without a hitch. No damaged brass either.