That guy in Muzzle Blasts was Dutch Schoultz and what he sold was his system for shooting a muzzle loading rifle accurately. He still sells it from a web site: Black Powder Rifle Accuracy System
Dutch is now in his 80's and doesn't shoot any more. Selling this is his only income besides social security. It's the best $20 I've ever spent on black powder stuff without question.
BTW, he now recommends Ballistol instead of the cutting oil.