The world of small arms is indeed intriguing. I tend to believe that many parallel (and some not so parallel) paths have been taken in developmental paths. Not just in firearms development but in all sorts of fields.
Charlie Cutshaw wrote a great book called The New World of Russian Small Arms & Ammo
. A very interesting read. There are firearms and ammunition that will astound you! I bought this book at Knob Creek last fall (he offered to personally autograph it too
) and Mr Cutshaw said he was working on a second companion volume to update the first as most of the information from the first is a couple of years old.
As I mentioned, this is a very interesting book. I found more on the subjectmatter here than I've found out in a dozen years of reading. Did you know for instance that the Russians developed not one but two different caliber underwater weapons families? I had only heard of one being developed. Also the machine pistols and tactical shotguns that have been developed is amazing.