Soviet Union SL doesn't have access to a standard bolt action and this is a mistake due to how weapon damage is balanced.
The maps they're featured on tend to be long range, "tanky" maps.
While the bolt action is by far the best long range weapon besides the scoped ones. It's going to be a 1 shot kill, versus using the SVT40 which takes 2 usually. The SVT40 just doesn't work as good at very long range compared to the bolt.
I'm sure it's an oversight but you're gimping their SL kit compared to the others.