I have a .338fed barrel for my TC and I absolutely love the cartridge for Elk, but honestly that is WAY too much cartridge for Whitetail. Get that DPMS in 7mm.08 ESPECIALLY for deer drives where multiple shots will more than likely take place. MUCH less recoil. Unless the deer in your area have grown armor plating, you really don't need a cartridge that size. Why go through the recoil and cost (the .338 aint cheap unless you reload and even then it's more expensive than alot).
In an AR based rifle, a good AR10 in 7mm.08 is just what the doctor ordered for a deer driver.