I have a .300 rum that I was going to build a .338 edge from and got to thinking about necking up a .375 or .300 rum to accept some solid match bullets intended for a .408 cheytac. I don't know if it would push the 408gr vlds fast enough but I would sure like to know if I have the makings of a 1500-2000 yd hammer before I call a reamer company. So any ideas or have I totally lost it?