I am thinking this is one of those Afghan shop made pistols. I have seen a ton of stuff that the Afghans have made while I was in the military.
They can turn anything into a gun. If I had to bet, I think that they took the frame of a webley and made the receiver.
I watched for 7 years as Marines and Sailors brought home Afghan weapons from the war. And maybe 10% were ever really what they thought they were. Lots of faked calvary pistols and martinis.
The idea of a single shot is common with them. As if it could fire once to kill a Russian then take their AK, they would use it.