What is the twist rate in a interarms mark x in the 308 win caliber?

Use a cleaning rod with a patch on it. Lay the rifle down with the rod just entering the chamber end of the barrel. The patch should be seated into the lands. Put a piece of masking tape on the cleaning rod near the handle. Mark a spot on the tape. Lay a ruler beside the cleaning rod and make a note of where the tape is in relations to it. Slide the rod into the barrel and note when the mark you made makes one full revolution. Stop. Measure the distance. Chances are it is 1 in 8".