Here's the rest of what he sent me on it.
1. Butt plate - Sea Service 1746 and later also Militia Muskets
2. Stock- The color and texture tends to indicate that it was once painted
with black tar. Sea Service
3. Amount and pattern of rust on barrel, lock and bayonet. Indicates one
of two things, either this gun spent a considerable time around salt water,
or else the barrel, lock and bayonet are old extremely rusty replacements.
4. The Lock - Although I cannot read the markings, I believe it to be a
pattern 1756 lock. (stipulated as being on the 1778 Bright & Black)
5. The sideplate - Meets the criteria of being the same outline as the
Land Pattern, but flat. (stipulated for all Marine Muskets after the 1757
Bright & Black.)
6. Ramrod thimbles - No entry thimble. 3 upper thimbles. All for wood
rammer. Consistent for Marine/Sea Service muskets. However, look at the
forward thimble. The distance between it and the second thimble is
different. The thimble has been moved back.
6. Nosecap - Not original to the gun. A later addition. Was probably
added when the barrel which has been cut back from 38 to 36 inches long was
done.
In my opinion what you see is a 1778 Black Sea Service/Marine musket that
has seen many hours in the armory of a sea going ship.