Take the entire rifle apart and degrease everything. I use windex for all that and cleaning. Make sure you use breech plug grease or else it will seize up. Also, when you tighten the plug, make sure its only finger tight. It doesnt need a lot of pressure. I'd start with 70 grains pyrodex RS or pyrodex P. A 385 or 410 grain hornady great plains conical should be an excellent shooter. Just make sure your rifle has an actual recoil pad and not that plastic butt pad crap. You "bolt" is easy to clean as im sure you can tell from just looking at it. All you need to do is soak the plunger in hot soapy watet and scrub it with an sos pad.

i use a simple .54 cal bore brush to clean out the breech plug threads and then a bore mop soaked with windex to clean out the threads in the barrel.

Theres no need for you to remove your barrel every time you go to clean it. I only take mine off maybe 3 to 4 times a year to fully clean the rifle.

I shoot a cva staghorn and its pretty much the same as a buckhorn.