What caliber is the rifle? If it's a .308 then the twist is 1 in 12". But you can find out by putting a starting mark on a cleaning rod that has a fairly tight patch on it. Then put a mark on the rod closer to the handle. Then start pushing the rod in. When the mark near the handle has made one rotation then put another mark on the rod. Pull the rod out and measure the distance between the begining mark and the end mark and there is your twist rate. Obviously this will only work with a rod like a dewey that swivels at the handle.
