I have not used this particular service. However, I do have a couple of custom-made ML bullet moulds. One is a .50 cal, 320-grain "Elmer Keith-style" semiwadcutter with a small base cavity and thick skirt walls I designedfor a .50 back in the days before there were any commercial bullets except round balls for use in muzzleloaders. I thought it might let me take shots I'd been passing up with round balls due to my imagination that balls didn't have enough penetration. I've since reconsidered this, at least as far as deer hunting is concerned.

Here's another maker..... http://www.hochmoulds.com/