I've read several books on Stalingrad, fascinating and horrific (Either side).
The Soviet Army was not as poorly equipped from what I read. I think there was a point in 1941 or early 42 where they didn't have enough stuff to go around but by the middle to end of the battle for Stalingrad the Russians were the much better equipped army. They had fully fielded, trained and equipped divisions in reserve...
I think the "Crisis" point for the soviets was getting caught flat footed after killing all of his officer corps...and the massive setbacks early in the war(1939-1941). Once Soviet Russia gasped for air (Entangled the German Army in Stalingrad) and cranked up the machines to produce the stuff, that war was over, All but the fighting and 1 million more Soviet Soldiers. (I am always amazed at the apparent lack of concern for casualties, the human wave was a real strategy for them)
If your rifle is made during WW2 (Pre 45), it served someone. I dont know of any way that you could figure out when, where, or who... I like the rifles from the late 30's and early 40's. I figure there is just about zero chance that between 3-4 of them one of them was somewhere interesting!
I Highly suggest reading "Stalingrad, The Fateful Siege: 1942-1943" by Antony Beevor if this interests you.