I can't imagine using Musket caps on any percussion gun unless I were a re-enactor using a military style gun, shooting blanks.
A CAPPER is a tool that holds percussion caps, and is used to help place them on the nipple, particularly in cold weather when you don't want to be touching any bare metal to your skin! Its also a safety tool, as it protects your fingers and thumb from serious damage or injury should any cap- including those musket caps-- fire as you are pushing them down onto the nipple bare "fingered"?
Cappers come in a variety of styles, made from steel, brass, and even heavy leather. Considering the cost difference of buying and shooting musket caps, the capper will pay for itself after using it to shoot a couple of hundred caps, just in practice.
I personally use a Tedd Cash oval, brass capper for my percussion shotgun. And, I use ONLY Standard #11 caps- not the magnums. The Capper is designed to hold 100 #11 caps, so I can dump an entire can of caps into the cap, give it a couple of shakes to right the caps in the well, and close the top. I am good to go with that capper with just a shake of my wrist to have a cap drop down into the spring holder. Since my entire hand covers the capper, the "rattle" of the caps is muffled so that only I can hear it- and probably feel it rather than hear it, if truth be known. I Do NOT wait to cap my gun until game is close.
If carrying a capped gun concerns you, there are plenty of options available to protect the gun from an accidental discharge, while having it still read to shoot in quick order. PT me for that information, as that is off-topic here. :thumbsup: