While a well placed 22 is more than adequite to drop a small deer in its tracks, probably a 22hornet is the best way to keep it legal.Old John McDonald ,gatekeeper of the Sooke Lake watershed shot hundreds of deer inside the fenced off new plantings and all he ever used was a BRNO 22 hornet with a ghost ring peep sight.You just don't need anything bigger if you can shoot it straight.In terms of wounding game,I'd far rather us a small caliber rifle than a shotgun with shot,which is lethal enough-at very close range but too many deer die from a pellet in their guts( I know farmers on the gulf islands who refuse to let people come on their property for this very reason, legal or not)
About 50 years ago I knew an old lady who shot a lot of Cougars with a 22,she had a chicken farm up the frazer valley and the cats were a plague, so when her dogs started making a fuss she went out with a lantern and her 22....the old lady said that 'cats didn't have a heavy bone structure and a 22 was all you need'