The wartime production Nagants aren't really as bad as they're thought to be. In fact, I bought a 1943 manufactured one a couple of months ago whose machining was so rough that the bayonet wouldn't even slide onto it, but when fired, severely outperformed my hexagonal pre-war 1927 Nagant. At 100 yards I shot about 3 inch groups, which is great in my opinion, as I'm an inexperienced shooter.
Bear70 is right though; in any case when firing any old firearm, there's a slight risk. As long as you inspect the weapon and get it looked at and OK'd by a gunsmith, you're golden.