I'll second that Kev, the other thing to consider is that for Normandy and Market garden he was in command of the 101st Airborne's artillery . In all likely hood, besides his personal sidearm, he probably would have carried a carbine, maybe folding stock, maybe not. I know there are other senior officers in the 101st and the 82 who carried M1's. But I haven't found anything so far to suggest he did.
Tim