I built this .50 cal. muzzleloader a couple of years ago. Friend had a Ruger single action grip frame. I machined a block of 1018 to fit frame and make the receiver. Made all parts except the grip frame, 6x48 screws, and nipple. Sighted in at 25 yds 30grs FFFg .495 round ball 5 shots made one large hole. Recoil about = to 1911 45 acp. Loaded 50grs FFFg .495 round ball. Good groups about 6" above point of aim, but recoil on level of 44 mag single action.