Back in the Age of Sail there was a very particular weapon called the swivel cannon, small guns capable of (comparatively) rapid fire for harassment. The 47mm QF 3-pounder by the noble Vickers company is the modern day swivel cannon. Operated by two men, it can deliver rapid and accurate fire at up to 2500 meters. With the aid of trained snipers and quality optics it's not unheard of to score hits against enemy personnel from up to four kilometers. Aiming at a ship-sized target one could hit it at up to five kilometers. The weapon is usually fired by one man as an oversized rifle while the other reloads or acts as a spotter.