The sort like the old Lyman FL hand dies. They are a puzzle. What caliber could it be? How did they make it? Why? Here are a couple of my latest finds, the back row is an unknown(so far) on left and a .300" bullet sizer?(full of lube) for 7.35 Carcano on right, the front row R-L is .44 American, .455 Webley, .45 ACP, and I will leave the one on the left as a test (hint: not 7.62x39 but invented about the same time) Anybody else find these kinds of tools interesting?