I've never shot one in the neck, but trained my daughter to do so with her first deer rifle, a 223 AR-15 that I built for her. I did this on advice of others who only use 223 single shots. Never have seen one missed or wounded, but have seen many killed on the spot with this shot. My daughter was 8 when she took her first deer on her first hunt at first light, when two bucks began sparring in front of her. I put the 223 in her hands mainly because of her size and recoil worries and she did quite well with it for years. With her new AR-10 in 308 she has been trained to shoot broadside, into the chest from the front and right up the rear exit, another shot that has devastating and immediate results with little or no meat loss. Even though I'm confident that she could take a head shot, she is an antler hunter and doesn't shoot doe's usually. She is 18 now.
And yes it's legal to use any centerfire cartridge here, rifle, pistol, or revolver with any expanding type bullets commonly used for game, no FMJ's, no more than 11 cartridges in magazine and chamber combined. No full auto's of coarse.
I'm not sure why people get upset over someone elses business, or why they would try and start something here, but again if it's legal and it works for you, you're the only one who has to live with it. If it makes you uncomfortable don't do it if it makes you happy kill em any way the law allows.