Badger Brown You might, just might, get an inline shooting a sabot, to be able to reach out accurately to 300 yards....but you're going to need a scope. This has already been mentioned.
Back in 1863, one of the world's most famous big game, and dangerous big game, hunters, was an Englishman named John Forsyth in India. In fact, since he was going after tiger, rhino, and elephant, he wanted a huge projectile, with plenty of velocity, and as flat a trajectory as possible, and he didn't have access to a reliable optic sight. So he came up with Forsyth rifling.
Even with his custom rifling....his absolute max range...was
200 yards. Yet although his rifles would shoot well enough to be accurate out to 200 yards, he had not encountered a situation beyond 150 yards where it would've been possible to make a shot, and he, himself, and not taken big game, dangerous or otherwise, at more than 100 yards.
Now, of course, he never hunted on the plains of North America...so his observations may not apply to where you are, but I'd suggest you get a rifle that shoots a .45 caliber, conical projectile, that is known to be accurate out to 200 yards. Now that might be a .45 or it might be a .50 shooting a sabot holding a .45 caliber projectile.
The
Tryon Creedmoor, and the
Tryon Match as well as the
Gibbs Rifle will all reach out 300 yards and farther but...
As mentioned, they are being used on known-distance target ranges, and the scoring areas are often much larger than what you'd need to hold for a group to be a successful hunter.
LD