As a full time hog hunter, which is what I have become since moving to Florida, I would not use a .223 on hogs. Yes it will kill them. I have killed 3 hogs with a .22 mag. Then I pulled a shot and hit the hog in the jaw and it ran so far it left out property and was not recovered. All I had was the hogs teeth.
The .223 will work for head shots, but you really need to be close to the pigs. Pigs move around more than anyother animal I have ever hunted and a 100 yard head shot is very hard to come by. Espcially if there are 15 pigs in the herd.
Please understand the anatomy of the pig. It is VERY different than that of other 4 legged animals.
Go to
http://www.texasboars.com and read the forums for anatomy pics and lots of good advice.