It's a tool that aids in making accurate shots in mixed terrain such as Idaho, Montana, Wyoming, Colorado, New Mexico, Utah, Arizona and Texas hill country.
WHY?
This being Long Range Hunting with the goal of making humane kills at significant distances. It's critical to understand the effects of cant when your shooting from various shooting positions in adverse conditions. Terrain features are mixed timber, sage brush, coulees, steep gullies, ravines, and draws. Rocky canyons and steep mountains some greater than 20+ degrees. Weather also effects our hunting by adding fatigue and exhaustion to the equation. Rarely have I had a decent rest to shoot from. I've been on my belly, face down and my body is twisted in order to make the shot. Cant is the major factor effecting accuracy even at close distances. Shooting off of a tree limb at a 35 degree angle on a slope with your target moving through cover is a tough shot to make. ANY cant or breakdown in your shooting form results in a missed shot or a wounded animal.
2 years ago hunting in Utah we located elk over a mile from our location. It took us several hours to close the distance. When we finally got in range the elk were above us at a 35 degree angle, moving single file up a steep chute.
We had to lay down and prop our rifles on any available support. I chose a large boulder and wrapped myself around it on my back with my rifle stock supported by my heavy jacket. The elk were moving up and around junipers and boulders. Maintaining the rifle level was difficult, my position was effecting my breathing, my body wasn't co-operating, and the elk were getting higher and further away. I was able twist my rifle into an angle that was level, making a one shot kill at "Point of Aim - Point of Impact (POA/POI)". My partner used several logs to build up his position and made a great shot as well. Levels, accurate rifles, good ammo, proper sight- in, come ups to 1000yds and lots of practice are just part of process of a successful big game hunt. Adapting and overcoming obstacles, bad weather, minor screw ups and just staying focused to the very end assures us all success.
Gonzo
SEMPER FIDELIS