If I am buying an AR15 rifle to hunt deer then get a 5.56 or .308 caliber rifle? Ammo cost/ distance consider?

that definately depends on the range you expect to hunt at, and how skilled you are.

i would not try to shoot at a deer past 100 yards with a .223, also dont hunt with a .223 unless you are confident in your shooting skills. as long as your shot is well placed, then i guarantee that the deer will go down. Also like Mike said a heavier bullet helps, but is not necessary

if you do not fit the above then get the .308 (are you looking at dpms??)

A .308 is the best caliber (of the two you listed) for deer, no question. In many areas the 5.56 is illegal and it is not an ideal round anyway. Only an experienced marksman should even consider using a .223/5.56 because shot placement is very important.

An AR15 is not a great hunting rifle and in some areas hunting with a semiautomatic rifle is also illegal. BTW, a semi automatic .308 is not a AR15, it is closer to an AR-10 (except the AR-10 is trademarked, I believe).

The range of the rifle is very much dependent on the user and the equipment used. Just as snipers generally use bolt action rifles, hunters do as well. I would not attempt a deer at more than a 100 yards with a .223/5.56. A .308 will easily take a deer beyond 200 yards depending on the skill of the hunter. Hunting ammo will range from $0.50 to $1 or more per round for either caliber, but .223/5.56 practice ammo is cheaper than .308.

Last time I checked, 308 Win cannot fit into the mag well of the AR15. If you're really interested in hunting with the AR15, I would suggest a intermediate cartridge like 6.5 Grendel. If you absolutely are set on hunting with 5.56, I'd suggest heavy premium hunting bullets such as 62gr and 70gr TSX. Never deer hunting, but I have taken good sized hogs from as far away as 300 yards with my AR before. For deer, I'd limit myself to about 200 yards. At that range, you'll still have about as much energy as 357 at the muzzle.

Been hunting with 223 for almost 10 years. Shot placement

In the state that I live in, it is illegal to use .223 to deer hunt. Around here .308 ammo runs about $17.96/20 for decent deer hunting ammo. Most people can';t shoot deer much over 200 yds no matter what rifle they are using.

I am not a fan of .223 on deer, however lots of people have done it. Just make sure it's legal in your state

You can but an AR-10 in .308, .243, and at least one other caliber that is escaping me.

I don't know specifics but a .308 goes much farther and has more energy at all ranges. The 5.56 has a tendency to tumble, which is why the military uses it. The round is meant for wounding shots which are fatal if untreated, but the don't drop an animal like a .308.

I've seen .308 that costs more than 5.56, but I don't know which one generally costs more.

5.56 does not have sufficient power to cleanly and consistently kill deer.

If you want an AR for deer, take a look at Remington's new .30 Rem AR cartridge.

Well a 308 will take the deer down no problem but u pay 15 for just cheap soft points. You can pay 4 for a box for a 223 but may need 2 shots if your not a great shot now a shot through the heart will take the ***** down. 308 more accurate as well like 1000yards range for deer. But maybe 600yards for 223. 223 can shot more because maybe you want it to be semi tactical as well. But a 308 has more accuracy at longer ranges

the ar-10 has the .308 get that, the 5.56 is to small