.223 would probably take a fawn down up here but I would have many reservations about a shoulder shot on anything else. 180# FD is a 2.5 or 3.5 year old in MN. I doubt .223 would have enough energy for a clean kill, there's a lot of tissue mass. But I don't believe you need an 7mm STW to take one either.
Sounds like a North/South pissing match.....My deer is bigger than your deer
From my own experience Muzzleloading this year a head shot might seem like a good choice but I had a shot at a huge doe and she stepped away just as I shot. I ended up clobbering a fawn in the face, removing most of its lower jaw. I trailed the deer for a mile. Until I lost the blood, but found out that 2 guys I was with saw a deer with a huge clot or something hanging from its face eating in a corn field half mile from were the blood stopped. If a 285 grain shot to the face at 50 yards doesn't at least drop the deer momentarily, the slightest misplacement of a 68-70 grain bullet would yield similar results.
Yes, I did finally take the fawn the next weekend. Still had spectactular backstraps!!
I say just go with the laws because at least HALF OF THE TIME, they are in place for a GOOD reason!!
KH