My ML hunting is with a flintlock.
I carry three premeasured charges in tubes and then 3 patched balls in a loading block, plus the shot in the gun. When I'm hunting the farm country around home, that's all I carry for reloads. I do generally keep powder/balls/patches somewhere in the truck or otherwise somewhere I can get to if I need them semi-readily.
When I go into bigger woods and places where I can't or won't be back to the truck all day, I'll carry the same tubes/loading block, but then also a horn with a measure, a shot bag with a handful of round balls, and a baggie with some precut, prelubed patches. That lets me restock my reloads as needed. I usually have a small backpack or similar with me then and put that stuff in there. I don't need it in a hurry, I just need it if I blow through my reloads.
For supplies, I carry spare flints, and brass hammer/turnscrew that will let me service the gun and sharpen the flint, a ball puller, a few patches, and some alcohol wipes. I usually have a cow's knee stowed somewhere, too, just in case it's needed....and with a flintlock, when you need a cow's knee, you need one.
