antique pump shotgun

[dave]

A friend of mine just inherited a very old hammerless pump gun. It looks like a browning with the squared off receiver but it has 2 triggers facing each other. Pull the rear trigger and it shoots, push the front trigger and it re-cocks, assuming its there in case of a misfire. Aside from a serial number there are no marks on the gun, doesn't even say what guage it is. Think its either 16 or 20. Also has a solid rib barrel, when you pump it the side of the receiver slides back, and a large block slides out of the loading gate underneath and has what looks like a knife blade on the side. Any help in identifying it would be greatly appreciated.

[Richard Simmons]

Like this?
http://www.gunauction.com/buy/11732020/guns-for-sale-curios-relics/shotgun-curios-relics/union-firearms-company-rare-union-firearms-double-trigger-pump-shotgun

[dave]

It looks almost exactly the same but the left side of the receiver is flat and doesn't have that metal insert(?) on the front lower left side of the receiver and the screw pattern is different.