That is a VERY nice looking pistol!
That is one of the TALO guns. Here's a link to their website listing for this Model, but they only show it in .45ACP (O9840CCU) on the website. The frames are aluminum alloy according to the TALO listing.
New Colt Combat Unit Models ? TALO Distributors Inc
Obviously Lipsey's copied the information incorrectly. I would be hard pressed to return that one if mine. Colt has been making Commanders out of aluminum alloy for decades.