I need help, any info will be greatly appreciated. I just picked up this smooth bore over/under percussion gun and can find no info anywhere. The bbls are 40" long and the bores measure about .50 (my cheap digital calipers fritzed out, the manual scale only reads tenths). There is a button on the tang that when pressed, allows the bbls to be rotated either clockwise or counter. The sidelock is marked "M B Williams" as are each bbl. No other markings are visible.