"Early 1700"? Definitely smoothbore. There are still a fair number of early 18th century guns from New England that would probably qualify for the nebulous title of "barn gun". No buttplate, or sheet iron buttplates nailed on, simple sheet iron triggerguards, etc. Of course, if you want a lock of this time period, you're pretty much S.O.L. If you're interested in early 18th century guns, the single best book for you to get is "Flintlock Fowlers", available from Scurlock publishing (the "Muzzloader Magazine" people). There are decent photos of several guns that would be suitable for recreation.
As much as I like them, I truly believe that for most of the 18th century, the "barn gun" (meaning those of "rifle type form") is pretty much a modern romantic fantasy. The "barn gun" as it is usually recognized seems to have basically come about in the early 19th century, and there seem to be rather large numbers of barn guns that still exist, primarily from the Lehigh and Berks county areas in PA. My VERY strong belief is that in the 18th century, a rifle had a buttplate, sideplate, etc. because that's just the way they were supposed to be. The average gun would generally have a bit of carving here and there as well. I think that the no buttplate, no sideplate, no nosecap, sheet metal triggerguard type gun just simply was not done in the 18th century.
The 19th century "barn gun" would also be considered ROUGH. So much so, that most moderns simply could not stand it. Rough, oversize wood, little finish, and probably no finish. Literally "lock stock and barrel" and that's it. It goes "bang", with NO effort wasted on fit or finish.
