Looks like a Rollfast (Snyder) right when they went to forward dropouts. I'll agree with above, early postwar, maybe 46-50 before they had the elongated dropouts. The shape of the frame is Snyder for sure. It may have the serial number that shows the year in 2 digits, reversed. Here's a 48 Rollfast that shows the dropouts, but looks like it has had other newer parts added.