Well, it may surprise many, but in the RCN, we are not paid to shoot hand held weapons. We are paid to fire big guns, big torpedoes and big missiles. The amount of time dedicated to small arms training before force protection became a thing was a few hours of refresher training before going to the range for the annual qualification shoot - which in those days, you could hardly fail if you were capable of hitting the side of a barn with a shotgun at 5 paces.
The most used small arm on a warship is the gunline gun, used to pass the light messenger in a RAS.