I’d check out a ballistic calculator. I ended up building a SML 45 cal. And it hits like a hammer.
I live in Allegheny County (Pittsburgh, PA) and we are shotgun/muzzleloader only for firearms season. I picked up a used Smokeless ML from a member hear last spring. It is a Rem 700, with Hank's magnum rifle modules setup. Using IMR4198 it is a tack driver. With a 100yd zero it is +2 MOA for zero at 200yds and +6MOA for a 300yd zero.
I fired a 3-shot group at 300yds from the bench and it measured about 2.75 inches. This meat in the freezer no matter how you slice it. Oh, I was shooting Parker 275gr Black Max bullets. These SML's are pricy, but they are awesome!!!
However, I do regret selling the Remington Ultimate Muzzleloader that I had previously.
I had this one painted by Brandon at Custom Gun Coatings. He matched a picture of a paint job I saw on another forum. I can't make the pic small enough to post here, but I have posted it on Snipers Hide in an SML thread.
https://www.snipershide.com/shooting/threads/custom-gun-coatings-camo-group-buy.6964125/post-9720983Anyway, 300yds is nothing to sneeze at for most people - especially with Muzzleloaders. I'm willing to bet typical loads out of Encore Muzzleloaders and similar inlines are slowing down rapidly at those distances. I would say that your best bet would be to find a used Rem 700 UML or a CVA Paramount if you can't use a SML for some reason (cost or local regs).
Good Luck,
Ross
