KSUFLY, The Navy's Bureau of Aeronautics widened the M-422's left pocket pocket 1/2" in 1941, added a pencil slot, and designated the jacket M-422A. More noticeable with the sewn seam down the right side of the left pocket. Also, the M-422A has the letters.. USN stenciled under the collar, and the lining was a rose/burgundy Bemberg rayon/twill type.
The difference between the M-422A and the G-1. The G-1 still has the pencil slot, but no sewn seam, just a sewn hole under the pocket flap, and the punched letters USN in the so-called wind flap, which the M-422A didn't have. BTW. we (new) pilots and the other older Officers called it the "tie protector" (wind flap) as it keep the black Dacron tie from being riddled by the zipper.
Has anyone here, ever asked why the "wind flap" only came up to 3/4 to the top of the zipper? The length of the wind flap was a stopping point for the zipper, and if zipped any farther, it would allow the leather jacket to cover the rank insignias on the collar. The CO and Air Boss was very strict on proper uniform dress code.. To combat the zipper from being any father up, we inserted a paper clip into the zipper band, so the zipper wouldn't go any farther..
Now you can go back to your squadrons and tell them all about those old Navy reg's..