Winchester Carbine serial number 647XXXX. This carbine has a receiver produced on January 3, 1945. What was the approximate amount of time before the rifle was actually assembled? Flip safeties and .30 round magazine catches are reported to have been available around April 1945. Could this carbine have been assembled with these features? The safety is JAO marked and the Magazine catch has no manufacturers marking. My assumption is that these parts were an arsenal add on, but could they have been installed by Winchester when originally built?