I have found the size of the flash hole makes a difference in accuracy in all muzzleloaders. Check your records, some nipples start out giving there best accuracy to start and some follow a predictable path or curve where as they flame wears the hole bigger they get more accurate then after a while as the hole gets bigger the groups start opening a bit then at a certain point all at once they get really big and you have to change the nipple. I found the Ampco nipples have a bit to small hole for max accuracy even though I have hardly ever had a misfire with them. Lee