Worked great in my Kinght original Disc rifle with the cross-fire breech plug installed. Not sure if it was part primer or a combination of both, but there was fouling in the first few inches above the breech plug after each shot. I swab between shots and consistant accuracy was mantained. Will cut a single hole @ 100 yards with the Scorpion PT Gold 260 grain and Remington STS primer. No hangfires. I use a undercoat of T/C T7 grease (slicky stuff) on the threads with a overcoat of Hornady muzzleloader Multi-lube for a better seal. Breech Plug spins right out after 15-20 shots. Dropping two pellets down the tube sure beats weighting out charges.