Wilson Combat has another option for taking your new AR-15 deer hunting besides coughing up the cost of an AR-10. A barrel swap and an investment in custom ammo gets you an AR in a new cartridge that they are calling 7.42x40WT. It’s a necked up .223 Rem. to .30 caliber. Maybe I'm being cynical but this sounds eerily similar to the 60 year old 7.62x39 cartridge to me.