I notice that I tend to twist my gun when I mount so that the bottom barrel is slightly to the right of my top barrel. Is that a bad thing? If so, what causes it and how can I fix it?
Twisting of your shotgun, or “torquing,” is usually caused by either your mount mechanics or a gun fit issue. How significantly it affects your point of impact depends on how severe the torquing is.
Let’s assume that you are mounting the gun properly and the issue is gun-fit related. Over the years, with a bit of trial and error, I’ve narrowed this problem down to one or more of the following three causes:
1) The shooter’s hand is too small for the grip. Grip length is the distance between the front face of the trigger and the front edge of the pistol grip. If this is too large, the shooter will tend to choke up on the stock, pull up instead of back on the trigger, and twist the grip away from his body. The best solution is a custom stock or an off-the-shelf shotgun with a smaller grip length. For ladies, Beretta, Syren and Zoli make good off-the-shelf options. For men, Caesar Guerini and Zoli have good options.
2) The bottom of the grip is too narrow for the shooter. This often occurs with a shooter who has a large hand and needs a larger palm swell. The solution here is either a custom stock or to wear a glove with padding on the inside of the hand, near the heel (hypothenar eminence). This forces the bottom of the pistol grip into a more upright position.
3) The gun has insufficient cast at toe or “toe out.” The toe is the lowest point on the butt, where the butt pad rests against the pectoral muscle or breast. Ladies and large chested men (body builders) typically need more toe out.
In some instances, the cause of torquing may be a combination of two or more of the above. It takes a bit of experimentation to figure out which of these issues, or combination thereof, is the cause of the torquing.