I recently purchased a Browning 20 Ga. SxS BSS shotgun. It has the single mech. trigger and is 90%. I got an extra set of barrels in 30-30. They came with another fore end manual exractor and fit the BSS tight. I have shot the gun 40 times and it works perfect. It shoots federal ammo ok but seems to like the old imperial stuff. There are no proof marks makers name or cal. stamped on the extra set of barrels. The barrels are like the Daniel Fraser with a partial rib just past the fore end and a block and ramp sight at the muzzle. Does anyone any guesses?