They're neither. Took one of mine to a bolt & screw company and theyUnderclocked said:They are suggesting the screws are #8? They look more like 1/4" to me.
Ya don't need to send your barrel to VVCG. They make a hanger bar insouthern utah said:Okie, They are 8x40 no dought. If you are going to an aftremarket forearm I would sugest you send the barrel to Bullberry or VVCG and have the dovetailed screw mounts installed. The are like the Contender. You can then use 10x32 "get anywhere" screws and if you are mounting a sling can replace the forward screw with the machined swivel stud.You could also got with one of their hanger bar systems.