I Just measured a set of spares that I keep on hand. The thread size is 5/32 and the front screw is 1 and 1/4 in length and the rear is 1 and 5/8 in length. Normally I grind off about one or one and a half threads from the front screw, since they sometimes bottom out against the action. These screws have a hex head though my older rifles have screws that have straight screwdriver slots. If you can't find them locally, Midway has them for $1.99 each.