I use either a SS 3' yardstick. I lay it on edge on top of the rib so that it extends over the guns heal. Then measure the distance from the yardstick to the top of the heal. Pretty much the same as whats been said except it may work better on guns with swamped ribs or middle beads.
Steve

Last edited by Rockdoc; 06/29/12 11:36 AM.
Approach life like you do a yellow light - RUN IT! (Gail T.)