Stevens Model 311 Series H 20 Gauge Double Barrel Side By Side Shotgun 3' Chambers 28' Barrels Double Triggers Fixed chokes Almost no signs of wear / Excellent clean condition Purchase includes eleven (11) Winchester Super Steel Magnum 3 inch #1 shells and twenty five (25) Remington Nitro Steel High Velocity Magnum 3 inch #4 shells But at the desired barrel band installation point above the forearm, my barrel OD measured a slightly oval. Three Piece Take Down (Screw Retained Forearm) GAUGE : 20. C double barrel shotgun store-brand Sears Model. Stevens model 311 series h 20 gauge Lot 158: Savage/Stevens Model 311 Series H Double Barrel Shotgun Auction Date: J20 gauge 28 ga.