As Rammer stated, the 222 is legal in SD. One of the first rifles that I ever bought myself was the Savage O/U with the 222/20 Ga. Barrels. I used it for deer for several years but you have to realize that as younguns, we hunted all the time if the gun you had would kill deer at 100 yards Max, then you used it when you got close enough to do the job. My remark abut the 22 Hornet was in reference to the 222 not being a decent rifle from someone who uses an even smaller rifle. I also used the 22 Hornet for a few years before I found out that it was not legal in SD.

I have also used the 6mm Rem and 223 for deer but unlike Rammer, I have seen quite a few big mulies hit with the 243 that didn't go down and a few that were never recovered. Not Many, but a few. Over the years I got a bad tatse for the 243 and no longer use anything smaller that the 25 caliber for deer. Also the deer where I hunt are 95 percent big bodied mule deer which probably take a little more killing tham the smallish whitetail here in ND where my wife works.

If you are careful with your shots, the 222. 22 Mag. 223 ,22 Hornet will kill deer but as a minimum for state laws the 243 should probably be the minumum. If I were making the laws, the 250 Savage would be the minimum. However for small deer, small rifles seem to work. Yes Back when, I shot plenty of them with a 22 LR. However, back then, there was no deer season where I lived and no legal or illegal guns for deer. When we needed meat, we shot it.