In Maine .22 mag is the smallest legal caliber. I hunted with a .22 Hornet one year only because I had no other choice if I wanted to go hunting (broken back). It did the job on a 215 pound (dressed) buck with a shot to the boiler room, but left absolutely NO blood trail to follow. Another hunter found my deer before me and tagged it as his own[:@].

After that I decided I would only shoot if I could drop it in it' s tracks - ended up making a brain shot on a spike on the last day.

The .22 calibers are definitely NOT ideal for deer, but they can do the job in the hands of a skilled hunter who chooses their shots carefully, as said before.