Many years ago when I was new to blackpowder and there wasn't an Internet to learn from I thought I needed musket caps for sure ignition in my hunting rifle but I found they caused more problems than they solved. Any number of nipples for standard #11 caps will work just fine, I doubt you could ever prove one brand to be better than another. If you have uncertain ignition the problem is most likely somewhere downstream from the nipple, probably a partial blockage of the flash channel between nipple and powder chamber, oil in there is sure to cause trouble.