So this is the one I picked up today. There really is a lot to learn about these classic firearms. This one has a Winchester receiver and a Springfield barrel. The guys behind the counter looked up the serial number and said it would have been issued in 1941. However the barrel was made in 1951. I've taken it home and field stripped it down to the gas tube. I don't own the wrench for it yet. But I imagine a screwdriver cushioned by a piece of cloth would work.