The newer Deer Stalker model has a 1 in 48 barrel twist that should shoot a round ball or bullet. The Investarms Hawken Carbine Rifle is a 1 in 48 as well. Percussion and flintlock guns don't shoot better with a short barrel (possibly worse but not much) but are much easier to carry because of the lighter weight.
Side lock TC Hawken and Renegades all had a 1 in 48 barrel except for the Pennsylvania Hunter that was made for round balls and had a 1 in 66 barrel twist. Having shot and owned a lot of 1 in 48 TCs I found they would either shoot a bullet well or they wouldn't but just about all of them shot a patched ball well once you found the load your rifle liked.
The Investarms Gemmer Hawken Rifle is much like the Lyman plains rifle with a 32" barrel that is 1 in 60 twist for patched round balls.
The flintlocks on these guns are just OK, some people have trouble getting them to spark but that can be corrected. I shot a flint Lyman Plains Rifle for a hunting season and it always went out off well.