Our game warden used to live a few houses down from me. He said he used to shoot them with a .410 also. I'd go broke doing that, 22lr is CHEAP...This is NOT an endorsement but just a story.
I had an Uncle who was a subsistance hunter who my Father said sometimes hunted frogs with a .410.
(My actual reaction.)
Dad explained that he would fire about a foot to the side and a stray pellet or two would catch the frog.
My buddy did find a gig head that is basically like 5 hyperdermic needles with barbs. They require no effort to stick in the frogs. That's important because most all of the ones I get are sitting on floating grass mats in the middle of small bays, not sitting on the bank. A "normal" gig would just push them underwater and they'd swim off.