44 Rimfire
They are all Model 3 Russians. The point being this is one of those that were "Factory Converted" from 44 centerfire to 44 Rimfire. You have to determine which batch this was from. It's definitely not the first batch of 1000 44 rimfires. They were serial numbered in their own range. Those guns were ordered in 1874.
The second batch was ordered in 1877. 7,000 guns were in that batch. This is the "Converted Batch" listed from 44 centerfire to 44 rimfire at the request of the Turkish government.
This was also the batch that was originally chambered for the 44 Russian, so the cylinder chambers are oversized for the 44 Rimfire. The Turks were fighting the Russians at that time and needed arms desperately in 44 rimfire.
However, only 2000 of these guns were of the Model 3/2. 5000 of them were the Model 3/3.
So you have to determine which batch this one is from.
Again, ITS A 44 RUSSIAN "CONVERTED" to a 44 rimfire.
I'm also seeing a distinct difference in color from the barrel/cylinder assembly and the frame assembly which often is a sign that it's a "non matching set". Since these guns were used during a war its possible that the parts were separated and re-assembled as a "NON-Matching " set.
So, your buddy needs to check the assembly numbers to see if they match. It might be an earlier barrel on a later frame.
So, you might have a Model 3/ 2-3....LOL
Murph