Ottoman shishana / shishane or boyliya?
 

Not quite sure exactly what this is, anyone have an opinion?

Given the length, I would call this a Boyliya (the name is derived from the word "boy", meaning a man's height). The shishanes tend to be shorter. Another main distiction is that boyliya is usually reserved to indicate a smooth bore, while shishanes were rifled.

The lock on the other hand is not of the Boyliya type.

Teodor

http://www.vikingsword.com/vb/showthread.php?t=21532
The lock is very Caucasian / Turkish to me.
Bulgaria, Turkey, Caucasus, I would call your gun, a Black sea rifle...

Best,
Kubur

Thanks Teodor, it is a smooth bore, the barrel walls look quite thin.

Thanks Kuber, I have never heard of a "Black Sea rifle", since it is a smooth bore I think it would technically not qualify as a rifle.

I am not good with the differences between locks, here is a detailed image if this is of any help.

You are certainly right for the barrel.
I think that could be an Ottoman lock, the old ones are very similar to the Caucasian locks.

Thanks Kuber, it has a very Ottoman shape, by all appearances this is quite an old musket.