I strongly believe that the older and less mobile you are, the more important becomes a [ridiculously???] large and powerful muzzleloading rifle with which to hunt. In terms of single shot rifles, I have stabilized on .72-caliber cap locks.
"Why?" you might reasonably ask. I agree completely with Mr. Steele. I live and hunt in west-central Montana where ranges for deer and elk tend to be short - that is, 150 yards is a L O N G shot. Terrain is severely vertical, and snow is reasonably possible during our 30-day season. This means that an elk, for example, shot at 60 yards that runs 75 yards before piling up might adjust a 45-minute field dress and quarter job to 8-10 hours of climbing up - or much, much worse - down to the animal, doing the dress-and-quarter, then getting it back to where moving it to transportation is feasible. Imagine the fun for oldsters like me. Oh, boy.
If you have a hunt for free-ranging bison, terrain is more forgiving, but your animal is 2-3 times the size of an elk. And trailing the bison who-knows-how-far complicates its recovery. And a bonus is the delicate flavor enhancement of adrenaline saturating the bison's muscle fibers during its attempted escape.
If you're like me and hope to someday have that muzzleloading cape buffalo hunt of a lifetime, that smaller rifle ain't gonna cut it. There are acceptably priced .72-caliber rifles currently available. If any has a rate of twist of 1:72 or more rapid, that rifle will stabilize conical bullets as heavy as 950-1000 grains (Steve Brooks and I worked out a design for which I will have him make a mold were that cape buffalo hunt occur).
Is there really such a muzzleloading rifle as "too big?" Since there is but one shot, I kind've doubt it. You can always load light. As I replied months ago on a similar thread, there's no substitute for cubic inches when hunting bigger game with a muzzleloading single shot rifle.
