I would agree. It is a cool photo.
As noted previously, I am wrong with alarming regularity. In getting a better look at the image (on my desktop computer as opposed to the iPhone), I can see the hair in the man's sideburns is very tightly curled, as would be expected with a Black or African-American person. Also, smoothbored muskets, including conversions, were imported by the thousands for use by both sides in the American Civil War, so it could very well be an American picture. It just doesn't look that way to me, though, for reasons I can't really define. Something about it just looks foreign. I would also stick with a late 19th - early 20th century timeframe.
It would be great if we could track down the origins of that photo.
Thanks to the OP for sharing it!
This reminds me of a story...
My dad was a gun collector, and he had a wide network of "gun buddies." One of these fellow collectors was from Alabama, back in the 1950's. This fellow was pretty well to do, and was also an avid hunter. The man was out in the woods of lower Alabama one day with his newest hunting gun, which I believe was a brand new Winchester Model 12 pump. He encountered another hunter, and they stopped to chat and check out each other's guns. They ended up swapping even, right there in the woods, and both men were happy with the deal. The other fellow was African-American, and went home with a pristine Model 12 and his pockets full of ammunition. My dad's buddy ended up with a heavily used but fully functional, all original Fayetteville musket.
Notchy Bob