I have to agree with everything that's been said so far. The woods were more open back then and a long barrel might not have been as cumbersome as it is today. Back in 2002 I worked on some guns that were recovered from a site in the Apalachicola River to the west of us here in Tallahassee. Recovered were the barrels and locks from five R. Wilson (R*W), Type G Trade guns and one rifle barrel. Our best estimation is that the guns dated to the 1760-70's time frame. Two of the trade gun barrels were complete, one at 48" and the other at 28"(I've had these at the CLA Show in the past). The 28 incher was probably shortened (well done) according in Wallace Gusler's opinion based on the spacing of the underlugs. Since then, I've worked on 3 other Type G trade gun barrels that were complete and they measured from 46" - 49" in length. The last 3 were loaded. Of interest was the 38" swamped rifle barrel in .62 cal. that was found with them. It appeared to be original length and had 3 rear sight placements, with the one farthest from the eye being used. The twist was one turn in 48", with 7 furrows and a right hand twist. I think the rifle was meant to fire the same size ball as the smoothbore Wilson trade guns. I haven't seen many longrifle parts recovered archaeologically. A Leman rifle barrel was found south of us in the St. Marks River along with a New England style rifle butt with the typical patchbox that comes to a sharp point (no side plates). I believe the Silver River Museum has 2-3 rifles collected from rivers, but I haven't had a chance to study them. A buttplate, sideplate, trigger, rr pipes and triggerguard were recovered from an Indian burial on the edge of Paynes's Prairie back in 1949. The buttplate and the triggerguard were a match with the early rifle that Wallace Gusler believes is Moravian from NC (I hope I got that right). Wallace thought the parts were probably restocked.
James Levy