Groundhogs, pasture poodles of Ontario & N.E. USA
groundhogs are 5 x the size of gophers. .22 is plenty for a gopher, I never shot a groundhog. I would guess a .22 would kill up to 50 yards with a headshot but not a body shot. I seen some huge groundhogs in Lethbridge. They must get to about 20 lbs
I figuratively cut my teeth on these guys in the '40s in SW Ontario, along the bottom land fields of the Thames River east of Chatham & Thamesville. I hunted with a neighbour, a barber who owned a Winchester pump .22 but not a plain L.R., still rimfire but fractionally larger and even then, almost impossible to buy ammo for. Myself, I used my father's .22LR Mossberg 46B, peep sighted bolt action, tubular mag, usually CIL Whiz-Bangs.
My mentor, Harland Smith, set the rules, no hunting until the first crop of hay was cut and the pups big enought to exit the den and look after themselves. Secondly head shots only on the adults after stalking to well within 100 yds. With a head shot, you had a body to pull out of the den by the tail or it was a "miss", we hoped. Body shots on adults were not made.
These were the days when the hot shots from Ohio would every year make a pilgrimage to the rolling country of central Ontario with their fancy single shot center fire fire .224 necked down from .25-20 cases and such, using jacketed bullets and big scopes. They wrote about their one-of-a-kind single shot rifles and the long range shooting in Ontario. These were the guys that took the 250 yds and up shots out even further, body shots of course with explosive results. This was exotic stuff in those days when even a .22 Hornet had been available for about 10 or 12 years.
Mean while, two or three evenings a week, Harland and I drove 5 or 6 miles in his Ford Model T, later a Model A to the flats along the Thames. On a good evening, we would score 3 or 4 kills each, head shots on the adults, body shots on the pups, using stealth, stalking and the curiosity of a ground hog to raise his head from one of the holes into the den for a look-see, after going to ground. I bought my prewar BSA Model 12 .220 at that time with the great vernier tang peep sight. I could if the head was plainly vissible get kills out to about 75 yds. None of this shooting, BTW was offhand, sitting, fence post or whatever available.
So, is a .22LR OK for ground hogs, very much so but go for head shots after stalking. This hunting was for me the prairie equivalent of a 500 yds stalk to bag an antelope!

The days when a kid could ride a bicycle for miles on country roads with a rifle slung over his shoulder and do the farmers a good turn by keeping the ground hogs in check.
I regret that I never ate a ground hog but knew people that did, cutting out the glands in the arm pits, skinning soaking in salted water and slow cooking the dark meat. Said to be excellent. And the old timers would dehair the hides, and cut them for boot laces, no round slippery synthetic cursed laces then.
