http://www.rockislandauction.com/viewitem/aid/67/lid/1668

The T2 submachine gun was Auto-Ordnance's entry into the ongoing competition to replace the classic Thompson submachine gun with something more economical to produce. It was a closed-bolt, select-fire design using a progressive trigger and a tubular receiver, along with stand Thompson gun magazines. Examples were made in both 9mm and .45 ACP, but it was the .45 version that the US military tested. Ultimately is was rejected in favor of the Inland/Hyde M2 submachine gun (which looks rather similar to it) - which was in turn quickly replaced by the much simpler M3 "Grease Gun" that would truly replace the Thompson in US military hands.