CVA sells a different breech plug that will accept the #11 and musket cap nipples. There is usually a order form in the back of the manual that came with the rifle. In that order form you can get the new breech plug and both the #11 and musket cap nipples mailed to your door by CVA. They are a nice thing to have. Some states demand that 209 shotgun primers are not used for hunting. In those cases use loose powders as your charge and that tiny #11 cap will fire it off without any problem. Musket caps have a lot more fire then the #11 caps but I find they tend to fall off the nipple more.