Hondo44's post got me looking closely @ the barrel & front sight.
It looks to me like a '50's 2-inch barrel with the shark-fin sight milled/filed down to match the pre-war rear sight.
And what's going on with that ejector rod ?
Was the original long one ADAPTED to the short barrel?
That seems like a lot of work compared to simply replacing with a short-barrel rod.

regards
Russ