Hi Jon,
Ive tinkered with muzzle loaders for a few years now. I started with a 12 gauge Pedersoli which I still have and graduated to a proofed 9/10 gauge Manton SXS thatd been honed out to 8.5/9 gauge. Because of the thin barrels I shot pen-raised pheasants with it using 12 gauge loads. Moving on I found a 36 gauge SXS that I also used on pen-raised pheasants (quite successfully I might add). My current muzzle loader is a 13 gauge Belgium SXS. Its a hardware store gun for certain but I hesitate to call it a JABC. The thing weighs 8lbs and its all in the barrels! Still its good having nice thick barrels with a 150 year old gun. Below is a photo of it along with a wild Nebraska pheasant I shot with it last year.

Ive also included a photo of some hassle saving things I have for the field. I make up pre-loads at home using sample vials held together with scotch tape, the BP in one vial the shot in the other. I have a short loading ram to get the wads started, and a device for holding and mounting percussion caps.

I carry a percussion nipple wrench with me that also has a nipple pick built into it. I marked my ramrod with a marker pen so that I can use it to judge, not only if a barrels loaded, but also that I didnt mix up my loads and accidentally load a double shot or powder load (surprisingly easy to do in the field). The worm screwed onto the end of the ramrod is for unloading. Carrying a cleaning brush is a good idea because after your barrels get good and dirty the wads start to stick when you reload.
Ive learned to pour in my BP and then run the brush up/down the bore, that way the burned powder residue doesnt block the passage from the percussion nipple.

Youll want to obtain a possible sack to hold all the tools and shot loads while youre in the field. I use a brown womans shoulder bag I picked up at Goodwill for a dollar, but you can buy fancy possible sacks made for BP enthusiasts. Below are two places to look.
https://www.trackofthewolf.com/https://www.dixiegunworks.com/I hope this information is useful.
Steve
PS I use hard plated shot, I'm not sure if it helps but it seems like a good idea.