Browning A Bolt 3: Base screws are 8-40 X 1/4″ long and ring screws are 6-40 X 5/8″ long. Base screws use a 9/64 Allen wrench and ring screws use a 7/64″ Allen wrench. Long action – Outside to outside of rings is 4.61″. Rings are .63″ wide. 4 Hole to hole spacing dimensions are .86″, 3.86″, .86″. Height of mounts from top of receiver to centerline of scope tube is – low .94″, medium 1.06″, and high 1.19″. Mount fits both left and right hand firearms.