Some posters on here are talking about gophers , not the 12 lb. eastern groundhog. When I was younger we shot hundreds of groundhogs(not in one day) with everything from .22 LR. to .45/70's and the like. Some places, noise wasn't a concern and ranges could be long, so we used 6mm's and a .240 Weatherby, other wise the .22/250 was king. The .22 and shotgun tended to wound them and they would make it back down the hole, and in some instances I believe the .22 LR., .22 Mag., and .17HMR would do they same, they'll die quickly from these but down their hole. Some can be very long range so I'll take the 22/250, the Swift, or a .243/6mm.IMHO