Tweaking your shotgun so that it fits you properly can mean more birds in the bag. You can do this by using the plastic shims and spacers that come with many shotguns to help you “sight in,” so that your eyes align with where the gun shoots. Once you do this, you can focus on the target, confident that the pattern will hit where you’re looking.
Shim kits typically include three or four thin spacers of varying tapers to adjust drop and cast. Less drop raises your eye, making you shoot higher. More drop lowers your point of impact. Adjusting cast (the lateral bend in the stock) helps center the gun under your master eye. Follow these steps to get your shotgun fit dialed in.
Shoot from a Rest
Before you start, find out where your gun shoots relative to its “sights” (the rib and bead). Set a sheet of paper or cardboard at 20 yards and draw an aiming mark on it. Look flat down the rib and shoot three or four aimed shots from a solid rest with target loads and without correcting your aim. This tests whether the gun shoots to the point of aim. If it doesn’t, and if the center of the pattern is within three or four inches of your aiming mark, you should be able to adjust it with shims. If it’s off more than that, especially to one side, shims won’t help, and you should consult a gunsmith.
Adjust Length of Pull
If you determine that your gun needs some adjustment, start by altering the length of pull. Add or subtract spacers to the butt until you can fit two fingers between your nose and the knuckle on the thumb of your trigger hand when the gun is mounted. That two-fingers’-width gap prevents you from punching yourself in the nose when the gun recoils. It also leaves the stock short enough for ease of mounting. If the gun doesn’t come with spacers, you can use a thinner or thicker butt pad to alter the length.
Practice Your Mount
Where a gun shoots from a rest and where it shoots when you mount it can be two different things. The more consistent your gun mount, the easier it becomes to fit a gun for drop and cast. Now that you have the stock length right, practice mounts with an unloaded gun. Think about standing with your nose over the toes of your front foot. Hold the gun parallel to the floor with the butt tucked lightly under the arm of your trigger hand. Push the muzzle out toward an imaginary target while raising the gun to your face. Ideally, your head shouldn’t move as the gun comes to your cheek, and you should be looking more or less right down the rib. When you can mount the gun the same way every time, you’re ready to fine-tune the fit.
Adjust Drop and Cast
The best place to fit your gun is at the range, shooting at a paper target that is at least 36 inches wide by 36 inches high. Stand 20 yards from the target, pick an aiming point, and mount and shoot as you would in the field, neither rushing nor taking time to aim. Maintain the same aiming point throughout. After four or five shots, the center of the pattern will be obvious.
If the center is too high, use a shim that increases the amount of drop. If it’s too low, you need less drop. Check it again following each adjustment. (Note: Some waterfowlers with very bead-conscious shooting styles can adjust elevation by switching to a smaller or larger front bead before they start fitting with shims.)
Use the same process to make cast adjustments, moving the pattern left or right. Most guns offer only one thickness for right- or left-hand cast, so you’re limited in what changes you can make if the gun shoots off-center. When you think you’ve got it right, shoot some straightaway clay targets from a low-gun start. If you’re crushing them without aiming, your gun likely fits.
Despite their advantages, shim kits can’t solve every gun-fitting problem. Some alterations require a gunsmith. Shims let you take a gun that is fairly close to fitting out of the box and dial it in, by yourself, at no cost. It’s a free investment that pays off handsomely in the field.
