Take a belted mag cartridge, 7mm mag or 300 mag, chuck it up in a three jaw in the lathe, drill out head w/ 3/8 drill, debure hole, trim off bottleneck end, this will drop into a 50 cal muzzle, belt will stop it at muzzle, load, clean etc thru this little gizzy, and will save your rifleing at the muzzle.. .. on my TC Encore, it stores without rattleing between the thimbles, on the rod and is always there to use.. HTH...Les

Easier than that, I've had all my bp's bore
relief bored. Something happens to the muzzle it won't hurt the rifling at all.

Sure makes loading slugs a lot easier.

George