I am thinking about buying an ar15, but my primary use would be to use it deer hunting.  I know the weapon is accurate, and shot placement is the key... but, is the caliber large enough to bring the deer down without me having to track it for long distances before it dies?  What suggestions do ya'll have as far as grain and type?  Also, this would be my first ar15.  I have military experience with the 16, and was wandering if the Bushmaster A3 with the 20" barrel is a good choice?  I need help!!!!!
Thanks in advance,
Alabama

Your State may not allow .223 for deer. I know Locals pop um withh 22's But you do want to put um down quick.

Although I have never been hunting with my AR15, I have heard it has a tendency to go straight through the deer.  Not to mention, you may get a lot of fragmenting which would be a pain when cleaning.  If your main purpose is hunting, you may be better off with a bolt action, or if you have the money...maybe a Stoner in .308.  I don't have much experience, but thats my $.02.

It's all about shot palcement. I've dropped them where they stand with a .38 snub, and I've tracked them over a mile following a bad shot with a 41Mag.

The .223 is a marginal deer load. The 64Gn Win Power Point (not power point plus) will be better than just about anything else in the caliber on deer, but it's still a just .22 centerfire.

 223 will work fine on a deer. I've dropped hells of the bastards with a 22 mag. Shot placement is the key....if you know that your rifle shoots straight, always put it in the head. that pretty much guarantees that you won't have to track him at all! If you feel more comfartble aiming into the mass of the body, do yourself (and the deer) a favor and go buy a gun that was made for medium to large game, like a 270, 30-06, 308....etc. I recently bought a 338 ultra mag. You can hit a deer in the foot and kill it with that thing. Pure energy is what's going to kill with shots that aren't placed well. Even so, if you trust your gun and yourself, the AR will work fine. Also, use a fairly heavy bullet with soft point or ballistic tip. Hollow points are great for close range, but lose alot of velocity when they expand. Good luck!!

[b]It's all about shot placement.[/b]

So true, all the muzzle energy or high tech bullet construction you can muster won't do the job if you don't put them in the right place.

While the .22 centerfires are generally considered marginal (too small by many) for deer the biggest downfall IMHO is that most factory rounds use a bullet that either fragments on the least resistance (varmint type bullets) or FMJ that pokes right on thru and deplete little energy and leaves a small wound channel in the animal. If you give the .223 a try plan on loading your own with a bullet designed to stay together such as the Barnes X or Nosler Partition (if they still make a .22 Partition). For common factory rounds the above mentioned 64 grain Winchester Power Point is about it.    

Alabama, like some of the others guys said, if you hit them right the .223 will do the job. I got my first with an AR a couple of weeks ago. Neck shot at 50 yds. and she never took a step. I've killed several deer with the .222, shot behind the shoulder and they never went over 50 yds. Alot of kids that hunt South Texas use the .223, my 11 year old niece got a nice doe this past weekend with a .223 Remington Model Seven. I'll let you know more after the next couple of days. I'm going to kill a couple of does for sausage. I'm using the Winchester Supereme 64 grn Power Point, but Federal Premium also makes a good deer load with a 55 grn Trophy Bonded bullet. Other people have posted success stories with the Federal also. Good luck...

It is shot placement. You have to be comfortable with yourself and what ever rifle you use. I have hunted with a Marlin 35 rem. shooting 200 grain for years and have done my share of blood trailing. This year due to an auto accident I was unable to use my 35 and had to buy something with less recoil. I bought a Bushmaster and went to the range. To make a long story short I used Remington 55gr pointed soft point on opening day and after 2 hours in my tree stand I had 2 does on the ground. The first was shot in the neck and dropped in tracks at 30 yards. Not a big deal. The second was walking through thick timber at 100 yards and a lung/heart shot dropped her in two steps. I'm not an expert as I have only owned my first ar-15 for 2 weeks now but I have filled 2 tags with it. I'm going to take it Coyote hunting this weekend. I think I will use Winchester Varmint loads for that.

Mine is an a2 but I do wish I had bought an a3. The scope sits up high off the carry handle and makes it akward to look through. Go for the A3.

You won't regret it.

If your primary use is to be deer hunting, as you state in your post, buy an inexpensive used sporting rifle in .243, .270, .308 or .30-06.  All will be better for a strictly deer hunting rifle.

That being said, deer just are not that tough.  I have killed many of them with the .223 and regular 55gr soft points.  The favorite deer rifle in my part of South Texas when I was a child was a Savage 340 in .222.  Those old men would buy a box of factory 50 gr soft points and kill any deer they saw.  They were not taking 400yd shots mind you, but for most deer hunting, the .223 will kill them just fine.  Shoot it enough so you can place your shot properly and you won't have any difficulty.

Bigger issue is knowing where to shoot them.  

I use a 444 marlin for deer hunting but I've been wanting a 50 beowulf maybe I can afford an upper before deer season next year all I've read says this would be a great deer gun ar style rifle

I have heard talk that a Nosler 69 gr+ Partition will do well as an AR deer cartridge. I've not tried it personally.

Regards,

FastVFR

Just got back from my Texas Hill country lease. I took a nice buck with a 115 yd. lung shot with my AR. The buck trotted about 25 yds and fell dead.  The 64 grn. Winchester Supereme worked perfect. I found it perfectly mushroomed and under the skin on the off side. I think I found the round that works best for me...