The 223 is enough cartridge for taking a deer when proper bullets are used. its a simple fact, and its kinda getting boring argueing about it. as long a controlled expansion bullet like a 60.gr. nosler partition is esed the bullet will expand and completly pass through the animal depositing a lot of its energy into the deer. it dosent really matter how much energy a cartridge has, a properly placed 222lr is better than a poorly place 300 win.mag.