I had one years a go, after doing some experiments with it I throw it away.
The problem as I see it.
PRB changes shape a lot as it penatrates, it flattens the folds back into a sort of ball shape but it does stay together; When you start using those littlle tools on it it will cause a 54 or any thing smaller to break up into peices, I never tried it on any thing bigger than a 54 cal so I can not say much about the larger cal. I was using a 45 and a 54 the 45 was loaded with 90gr RS the 54 with 120 gr RS.Lee