From Illinois hunting regulations:
http://www.dnr.state.il.us/pubaffairs/2 ... Sept03.htm
The legal ammunition for handgun hunting will be a straight-walled centerfire cartridge of .30 caliber or larger that is available as a factory load with the published ballistic tables of the manufacturer showing a capability of at least 500 foot pounds of energy at the muzzle.
From Indiana hunting regulations:
http://www.in.gov/dnr/fishwild/huntguide1/deerhnt.htm
Some types of handgun cartridges legal for deer hunting include 357 Magnum, 41 Magnum, 44 Magnum, 44 Special, 45 Colt, 45 Long Colt, 45 Winchester Magnum, 35 Remington and 357 Herrett.
The 357 Magnum is the lowest energy of the above list and as we know has a standard and very common load of 158 grain bullet doing about 1235fps or about 535ft-lbs of energy at the muzzle
Taken from Colorado's hunting regulation for deer:
http://wildlife.state.co.us/regulations/ch02.pdf page 3
Handguns, provided they have a minimum barrel length of four (4) inches and comply with the following criteria:
a. Use a .24 caliber or larger diameter expanding bullet.
b. Use only a cartridge with a rated impact energy of at least 550 ft. pounds at 50 yds. As determined by the manufacturer.
Many states also allow the use of 410 slugs for deer hunting, not all do but many states do. A 410 slug has about 650ft at the muzzle at best. When I chronographed slugs out of my Winchester 9410 I only got 1760fps or about 602 ft-lbs. 410 slugs are below 500 ft-lbs at only 20 yards from the muzzle and have lost half their energy by 55 yards.
Even a 20 gage foster type slug is just below 1000 ft-lbs at 50 yards. The 1000 ft-lbs has always seems to be high for deer to me even if it just muzzle energy and not on target energy. I have heard the 1000 ft-lbs minimum for deer before but have never seen any good science to support that claim. Much like the claims that you need to drink eight-8oz glasses of water a day. There is no scientific study that determines that either, but society latch on to for some reason and it became fact without science. None-the-less from a quick look at several states games law a few of which I quoted above it seems that the various State Divisions of Wildlife seem to think that somewhere between 500 ft-lbs at the muzzle to 500 ft-lbs at the target is a good minimum for deer hunting.
After personally taking a deer at 65 yard this year with my 410 slug gun delivering and estimated 270 ft-lbs at the target it seems that 1000 ft-lbs is a very high benchmark as a minimum requirement. I don't think 1000 ft-lbs is overkill at all and I have shot deer at close range, 35 yards or so, with a 12 slug and of the 3000 ft-lbs of muzzle energy from that 3" 1oz slug I would be lucky if a 1/3 of that energy actually was delivered to the deer. The slug punched clean through that doe on a quarter away shot that broke the far shoulder and pulverizes a crab apple tree beyond her and then keeps going. The fact is left the doe with significant velocity to do noticeable damage to the crab apple tree meant it took significantly less then 3000 ft-lbs to fully penetrate through that deer. Without knowing the exit velocity we can't say how much but it was quite a bit less then the 3000 ft-lbs and I would guess a bit less then 1000 ft-lbs.
I think 1000 ft-lbs is a good suggestion as a starting place, it is very adequate energy without being overkill. I do not agree that it is a human minimum.
As for buckshot specifically I have never used it to hunt, shot some water jug with it that about it. But it would seem that if 00 buckshot from a 12 gage will kill a deer then the same pellets from a 410 should work assuming that you can put enough of the 00 pellets were they belong in the boiler room. The velocity of the pellet from either is very close. And given the above arguments of energy is would seem that 3-5 pellets place in the boiler would be sufficient to kill a deer. Both the 12 gage and the 410 should be able to meet that requirement at proper ranges for the guns.
mcb