The H&R "DEFENDER" series began to show up around 1937-38. The "Defender Special" was the first of the .38 S&W chambered pieces. First models had non-adjustable front and rear sights. Later, circa 1940, pieces had adjustable front sights for height, and adjustable rear for windage. ALL the Defenders were derived from the H&R Model 999 Sportsman frame (early "NEW DEFENDER" models were 2" barrelled Sportsman .22 lr). My collection includes about a dozen "Defenders" - and the serial number ranges seem to be "batched" rather than sequential. Your piece should have adjustable front and rear sights and a "gold" bead set into the front sight blade. It will be an automatic ejecting, 5 shot revolver. Grip panels will probably be black nylon/plastic with that serial number. These guns weres produced as secondary firearms for use by security police and plant guards during WW2 when then S&W and Colt firearms were primary for military use. These guns are generally sturdy, well built and reliable revolvers. I've fired several of mine over the years and they are "fun" to shoot, using the proper ammo. Winchester, Federal, MagTech all market .38S&W ammo suitable for use in these old firearms.