Punt guns were usually custom-designed and varied widely, but could have bore diameters exceeding 2 inches (51 mm) and fire over a pound (≈ 0.45 kg) of shot at a time. A single shot could kill over 50 waterfowl resting on the water’s surface. They were too big to hold and the recoil was so large that they had to be mounted directly on punts used for hunting, hence their name. Hunters would manoeuvre their punts quietly into line and range of the flock using poles or oars to avoid startling them. Generally, the gun was fixed to the punt; thus the hunter would manoeuvre the entire boat in order to aim the gun. The guns were sufficiently powerful, and the punts sufficiently small, that firing the gun often propelled the punt backwards several inches or more. To improve efficiency, hunters could work in fleets of up to around ten punts.
https://en.wikipedia.org/wiki/Punt_gun?wprov=sfla1