I'm looking at a Gustloff 16ga over and under with ejectors and solid rib. Seller says its a world war II German pilots issue gun. It has an eagle over N proof mark under the barrels, cheek piece, buttplate with "BSW" on it, horn trigger guard, double triggers, scroll engraving, and strong case colors. I'm not sure its a military issue gun. I was thinking its a commercial gun. Any info on these guns would be greatly appreciated.