Eb1 is close.
I've killed deer with the .223 with bullets from 50 to 70gr.
Most any SOFT POINT bullet ammo 55gr or heavier will work well.
Avoid the plastic tipped ammo, as well as hollow pointed. One exception is the Berger 70gr VLD. I killed a deer last season with it from my 20"bbl Mossberg MVP at ~30yds with a heart shot. Bullet expanded and gave a 4" exit wound, or about like a 150gr bullet from a .30/06 at same velocity/range.
My favorite AR15 deer load uses the 60gr Hornady PtSpt, followed by the 63 and 65gr Sierra ProHunter and GameKing bullets. I bought a large amount of Hornady 60gr PtSpts (blems from MidwayUSA) several years ago, so it's my "go-to" bullet for either the .223 or .22-250.
The Winchester 64gr PtSpt has an excellent reputation in our area for deer.
I've killed more deer with the Hornady 55gr PtSpt because I've bought lots of them in bulk (1,000pc packs) over the years, as plinking and general use in various .22cf's.
Most of my "deer shooting" is with cast bullets these days, just because I can, and enjoy using a bullet I make myself. But, now that the shortages are over, it cost about the same for a 55-60gr .224" bullet as it does to gas-check a cast bullet.
I'm not especially crazy about the ergonomics of the AR, and much prefer my lever-action's. I'm kinda of a "wool plaid" kind of outdoorsman vs. ripstop nylon camo kind.
Love my l/a's and the .35Rem is probably my favorite.
A 200gr .360" FNGC doesn't do any better than the .223 on our smallish deer.
Watched 4 8pt+ and two "smaller" bucks on the corn in backyard last evening.
'15 should be an excellent year for deer harvest in the backyard!
Like last year, the bucks keep all the does ran off! With the 4pt per side or better requirement in effect for 10+years, the does get hit real hard. Getting harder each season to let 4 or 5 "too small" bucks walk and not see any does! But the bucks keep coming from "somewhere" though!