What is the value of a Marlin Model 26G pump shotgun in very good to excellent condition and what does the G mark mean?

the marlin 26 was manufactured from 1909 to 1915. it was offered in three versions, The series G {field grade} with available in a 26 30 or 32 inch smooth barrel in full choke. The Model 26 brush gun, with 26 inch cylinder bore The model 26 Riot gun, 20 inch cylinder bore The {G} was used by Marlin as a "field grade" designation. in 100% NRA condition. {seldom seen} this gun books at about $275.00 retailors most often encounter 60 to 80% condition and normally sell this gun for around $125 to $175.00 Mark S. Johnson Gun Smith/Master Stock Maker