Welcome to the world of sidelocks and cap locks. I got rid of my inline and now strictly use flint and percussion. I own 4 lymans, you cant go wrong. Unless I missed it, you didnt mention which type of gpr you were getting. I shoot the buffalo ballets and hornadys pa conicals( 50 cal only). these are both great bullets, weigh a little more than the round ball and no patch required. the pa conicals are designed for the slower twist barrels. speaking of barrels, you can get a hunter barrel for the gpr for a 1:32 twist if so inclined.