The Romanian WASR-2, 5.45x39 is actually the AK-74, which is a modernized version of the AK-47, 7.62x39. It is used by many of the former eastern block nations including Lithuania, Hungary, former East Germany and others. As stated earlier, it is a good round.
The Soviets designed it so it would tumble and yaw sooner when it hit soft body tissues, and create more severe wounds on the enemy. Plus the lighter, more streamlined projectile gave it greater velocity and a flatter trajectory.
However, you must use magazines and parts, plus the ammo specifically made for that caliber. It's available, but you'll have to look harder for it. The traditional AK-47, 7.62x39 is much more common, the components much more readily available, as is the ammunition. I know Walmart sells the 7.62x39 but I don't know if they sell the 5.45x39.
I had a Romanian WASR-3 and got frustrated because it was harder to find stuff for it, while the 7.62 stuff was everywhere. I eventually traded it for a Romanian WASR-1, AK-47, 7.62x39 with double stack, high capacity magazines specifically for that reason.
Both calibers shoot well, so basically you've got to decide how speciallized, or universal, a firearm you want to mess with.
