I got those rivets at ace hardware. The bolt cutter rivet tool is easy to make and well worth the effort. But, if you're going this route: cut the rivet heads to fit into the cutouts; dremmel out enough of the center of the heads for the barrel to fit in; put your receiver on and the rivets, press in the barrel; set the rivets; shoot, enjoy. I did turn down a bar so that it was a slip fit to make sure the rivet heads would clear. Here's a pic of the cutouts that are typical on non-bulged trunions. In the top picture, the slot above the flashlite is for the barrel pin. The front cutouts run top to bottem, and the rear ones run front to back. You can see the rear cutout and rivet hole in the top pic.