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in Keith Drapers book...a waterfowlers tail there is chapter on puntguns...makes for interesting reading....
you aimed above birds,clapped and fired as they rose up.

only if its muzzle loaded...or would be having a blast....well ACTUALLY there might just be a few micky loads in my ammo box to try out.....home rolled black powder,steel shot wad and load of steel...

shooting on the water is the fly in ointment there,,,,,,,
allowed up to 10ga I believe but dont think any bigger.
would be one hell of a lot of fun all the same....now for canada geese where there...