After starting with futuristic and modern weaponry and going through cold war era ones, Sledgehammer Games decided to keep up with some WWII firearms, first with the STG44 previously added, and now with the M1911 and MP40. Like previous weapons added via updates, they're coming first on Xbox One, and will not be available to 7th gen consoles
"We’ve brought a number of new weapons to Call of Duty: Advanced Warfare in the last few months. From the M1 Irons, to the futuristic CEL-3 shotgun, to classics like the AK47 and M16. This time, we decided to go back to our Call of Duty roots and introduce a new secondary pistol as well as a returning and fan-favorite SMG. The 1911 and the MP40 make a triumphant return to the Call of Duty series on Xbox One on September 29th – coming soon to PS4 and PC."
Source: Sledgehammer Games