I think we too often forget that back in the period, gun makers built to a pattern. If one of us could walk into an 18th century gun maker's shop in western Virginia or North Carolina and order a 5 pound sterling fowling gun, we would receive a gun that looks like, but wouldn't be identical to the gun from another maker. The main difference would be in the lock (most likely imported from England rather than forged in the shop), The barrel would be forge welded rather than the modern deep drilled and reamed from a billet. Other than these The gun received may look very much like the Carolina pattern fowling guns pictured in Grinslade's book, but it wouldn't be identical to any of them.
What I am saying is that the gun you purchase doesn't have to be identical to a gun documented to the 18th century to meet the pattern requirements. Sure, avoid a Siler Germanic lock on a Carolina pattern gun, but such guns do exist if uncommon. Iron hardware is uncommon, but a few exist. Brass will tarnish nicely and will not cause game alerting reflections in the woods. Don't allow modern preconceived notions to drive your selection of a fowling gun such as barrel length or choke. Do prepare to enjoy a gun built more or less in accordance with the desired pattern (or school).
Do avoid the battlefield pickup scenario. For one to be on the battle field to be in the position to pickup a discarded firearm, one would likely be on the winning side and already in possession of a firearm. Besides in the early F&I war, the colonists weren't often on the winning side.
