You know, there is a club out there that uses nail gun blanks to power a piston to hit a golf ball. It is so people with limitations and can’t swing a club can still enjoy the game.
There are also an assortment of air guns and devices that use blanks to launch golf balls. So had he converted a shot gun to fire golf balls, he might have had a game there…
And, there kind of is a “shot gun golf”. It is called sporting clays. You walk on a course which has stations. Each station has a different setup where you fire at 4 clay pigeons launched from two different positions. It is more varied and not as structured as skeet or trap. Each course is going to be different, and you can change up the stations through the season.