What is the value of a 12 gauge J Stevens Arms and Tool Co pump shotgun with a Browning patent dated Feb 7 1905 Aug 27 1907 no number or marking except full stamped in barrel?

That's the Model 520 Stevens. In typical condition they sell for around $150, really nice ones might get to $200-$225. There were military US-marked riot and trenchgun variants of the Stevens 520 than can reach over $1000. sales@countrygunsmith.net