I have never used a musket nipple. Do you know they size of the flash hole in the nipple?I happen to like the musket caps better for a few reasons. Easier to handle, more sure-fire with substitutes, stay on the nipple before and after firing, can reuse the cup with priming compound.
Do you have the ability to measure it? Once a #11 gets to .0385 it will cock the hammer and the accuracy goes out the window.Here are two examples of nipples. The one on the left is for a standard #11 percussion cap. On the right is for an Enfield CW musket, using the much larger musket cap. Judge for yourself.