Hi Trotmanj
What you have is a long gun from Morocco. And very typical of the style. Locally, it is known as Afedali. It comes from the Taroudant region and the Oued Sous Valley. It is one of three general styles produced in Morocco as identified by the butt stock style.
The snaphaunce lock itself officially dates to the late 16th century. But these locks/guns were in use by locals in Morocco through at least the 3rd quarter of the 19th century (progress was slow in this region). The lock on your gun is a locally made copy in the Dutch pattern.
The stock on this example appears to be generally un-decorated, with the exception of a few punch marks on the butt cap, and maybe the barrel bands. The gun stocks and barrels ranged from plain (like yours) to highly decorated and all points in between. Generally, these guns were built using three trades: Barrel making, lock making, and stock making (and final assembly). Often there is a makers stamp on the barrel and/or the lock. But just as often there will be no stamps or marks as the builder did not want the gun traced back to any particular shop as the guns were sold to both friend and foe alike. LOL
Historically, collectors of antique Eastern market weapons were primarily interested in the blades and armour, The guns did not generate much interest with collectors past the decorations, if any. And the fact that these Moroccan muskets were used by the locals for such a long period of time is the likely reason there are many examples still available today. In fact, during later, modern times dealers of antique guns would only take these guns in on consignment as the collector market was so small. That's the primary reason their collector values seldom match their European counterparts. There simply are not as many collectors for these guns. That said, strangely enough, in the last 4-5 years, the auction prices for these guns have been steadily going up. I don't really know the reason for this.
Judging by your three, small photos (need more and larger photos to judge condition) your musket appears to be in very good, unmolested, and complete (not missing any parts) condition. If so, this nice condition can off-set the lack of decoration on the barrel or stock that is often desirable. Thus, my shirt sleeve guess is that this gun could fetch $700-800.00 at auction. Especially if the lock is in working order.
Hope this helps.
Rick