It's fired by percussion cap. Flintlock is another monster all together. I don't have any desire to go that direction.
The hardware itself isn't old -- manufactured in 2018, in fact. The basic design, of course, is old, but the components are made of modern materials. Modern steel makes a huge difference in barrel accuracy, durability, and safety.
As Blind said, here in Utah there are separate deer hunting seasons for bow & arrow, muzzleloaders, and general rifle.
I'll try to take some pictures of the process. I've been working on it, getting parts fitted, but nothing really exciting to look at yet.
Muzzleloader update-- It's looking like a gun now. I have all the parts fitted to the stock now. It took quite a bit of time with blacking, removing a little wood, blacking again, removing more wood, ad nauseum until each part fit properly. It was a bit tedious, but I found the work enjoyable.
Now there is a ton of work to do with removing the excess wood and shaping the stock, then finishing everything.
Some pics of the whole gun, minus just a couple things, and some close-ups of the main parts that needed to be fitted.