The lyman Great Plains is an excelent "starter" gun.
There are two different Trade rifle models,,
the Great Plains Rifle; a slow twist 1:60 ,made for ball. and
the Great Plains Hunter; a fast twist 1:32 ,made for conical type projecitles.
That information, as well as caliber; either .50 or .54 should be stamped on the side of the barrel.
With proper care and a fair amount of practice(100 rounds or so) these rifles can reliably take deer size game out too 100yrds, with many experianced shooters doing much better. Sub 2" groups at 100 are not un-heard of.