I wouldn't use a varmint bullet on anything larger than a coyote. Look at all that edible meat in Charlie's hand. A hollowpoint would have trashed that, if it got to it. Lightly constructed bullets, varmint bullets, are made to expand on contact with small, thin-skinned targets. A deer will have the bullet blow up too soon for meaningful penetration, especially at 20 yards.
Even turkeys are classified as big game in Virginia, and as such require a bullet of 23 cal or above. No .223, .222 or .220 Swifts for big game. Deservedly so, too. But this is not a discussion about bowhunting anymore, is it?
If someone is hardheadedly adamant about hunting "medium" game with lightly constructed bullets, (or *gack* fmj's) from a sub-caliber rifle, I have no reason to converse with them. Plenty other folks around. Never argue with a fool...
Killdeer