E-Bay has lots of Arch punches designed to cut soft materials ie:leather/gaskets etc..........9/16 =14mm for .54 cal .1/2 =12mm for .50 cal and for patch cutting 1 1/4" for .54 ball not sure about .50 size or .45cal just measure a cut patch and go with that.Hardware stores and tool places can get them for you as well.A rubber mallet is needed so you don't peen the punch.Have fun...................Harold