This buttplate has the Remington Arms name, and is proper for post-1925 firearms. It has a slight curve and a lip over the top.
Remington 1899 Double Barrel Shotgun Buttplate (Curved w/ Spur)
5 7/32″ x 1 9/16″
3″ between inside edges of screw holes (top screw hole starts @ the heel and cut @ sharp angle)
1 3/8″ wide across center of screw hole @ toe
1 5/16″ long from center of screw hole to toe