Mosins were sighted in with the bayonets attached. Russian doctrine was that the bayonet was to be affixed at all times. The exceptions were while in storage and during certain troop transports.
They saw the rifle as a vehicle for the bayonet, as did many (most) armies of the time. There was even a formula amongst the Germans, Russians, and folks in that area to determine superior bayonet reach etc.
In essence, the infantry were only pikemen armed with pikes that just happened to shoot a bullet.
When you mount your bayonet, the point of impact will return to normal.