Its well balanced imo.
I did a lot of melee fighting with the "rifleclub", sometimes you need 4 hits to kill an enemy and its really short compared to the one hitting bayonett.
Yes, you can cause a lot of trouble if you manage to get behind the enemy lines. But that is not cause the rifle is overpowered, it is because a lot of people are unaware, focused on shooting and reloading or simply arent good in melee fighting, especially blocking.