Welcome to the forum. I also shoot the same rifle. I use a #11 cap system but your musket cap will work just fine. Is it better you ask? Remember, shoot loose powder only. Even though a musket cap puts more fire into the breech then a #11 it is still really not enough under certain conditions to ignite pellets each and every time. And I have never had a problem setting off loose powder with a #11. One problem some face is finding top hats or the musket caps.

They do make cappers for the musket caps. I saw them on a Traditions Rifle site a while back. OR If you want, you can get a hot shot #11 nipple, change that over to the musket one, and get #11 caps and shoot them. A good brass inline capper makes loading the rifle, even with a scope easy.