Had quite a long chat with my mate tonight...I will be having a bevvy on Thursday with a couple of local fuzz, one of whom was ARV until recently (coming up to retirement), so I'll ask what his views are on your point.
Personally, I would do the same as I do with a sheep... back of the head, or what is the skull thickness like of a deer, would a HV .22 penetrate?
If with a shotgun, where is the best place to dispatch a larger deer?
I know a couple of the local keepers on the big estates are called out if the deer is "on their land" when hit.
His view on the matter of dispatching a fallen deer other wildlife was to use a local wher possible or a Vet. The issue with Vets, is the delay.
Whwen I asked about a local civvy doing the deed, his take was that he'd call it in, advise the Boss that a local with a firarm and ammo would do the deed. He was quite happy with that... Especially as it would reduce 2hrs paperwork from even getting the HK out of the lock box!! AND, they would chuck in the pickup!!