Punt guns were shotguns, and mounted and tied down on a small boat. The person would aim the boat/ gun at a raft of ducks/waterfowl floating on the water and fire it.
A good shot could mean 50 or more ducks with one shot.
Yes, used for commercial duck hunting
A good shot could mean 50 or more ducks with one shot...... or the shore birds, their feathers were in demand for ladies hats and the bodies were used as delicacies at the shore hotels and restaurants. They were killing so many that by 1918 they were banned totally before the shore birds went the way of the passenger pigeon.
The Chesapeake Bay Maritime Museum in MD has a nice collection of punt guns.