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How your shotgun patterns determine the gun’s effective range, shot density, and wounding power. If your shotgun is for hunting or skeet shooting, patterning your shotgun helps you keep more pellets in the kill zone.
Shotguns fire three types of ammunition, excluding exotic types—birdshot, buckshot, and slugs. When firing birdshot or buckshot, the shot pellets leave the muzzle in a cluster that gradually disperses. This dispersion increases the farther the shot pellets travel.
The spread of the shot pellets is called the shot pattern. The characteristics of a shotgun’s shot pattern will affect the effective range of the shotgun, the hit probability at various distances, and the wounding power and lethality of the pellets. If you’re interested in hunting or competitive shooting sports, patterning your shotgun is essential.
It’s commonly thought that the pattern exhibited by shot pellets is determined by barrel length. The primary factor determining the shot pattern, however, is the choke tube or lack thereof. A choke tube is a cylinder with a tapered inside diameter that you screw into the muzzle of a shotgun.
Shotguns may ship with choke tubes, or you may have to buy them separately, but the purpose of a choke tube is to constrict the shot pattern to increase the pattern density.
This effectively extends the range of your shotgun. It’s important to remember, however, that the pellets lose energy at the same rate. The purpose of the choke tube is not to increase energy retention at range—it’s to increase the number of pellets that strike a target, maximizing the damage inflicted.
Choke tubes may provide either fixed or adjustable constriction, and each type has its advantages and disadvantages, depending on your preferred type of shooting.
It’s important to remember that no two shot patterns are alike, and there’s no way to render shot patterns 100% consistent with each other. There will always be a somewhat uneven distribution. There will always be holes or gaps in the shot pattern. Your aim is not to eliminate any unevenness or inconsistency — it’s to minimize it and maximize density.
You may have asked, “What distance should be used to pattern a shotgun?” The range at which you pattern a shotgun is traditionally 40 yards, although this is reduced to 25 when using .410-bore shotshells. The reason for the 40-yard standard is a matter of debate, but this probably corresponds to the maximum range at which shotguns were considered effective.
When patterning your shotgun, you’ll be counting individual pellet strikes. But it’s worth mentioning that the number of holes in a paper target is not necessarily reflective of the number of pellet impacts.
When you fire a shotgun, and the shot cluster leaves the muzzle, the pellets at the front collide with the air, thereby protecting the pellets in the rear. This is called drafting and is an air-resistance phenomenon experienced by racecar drivers.
The rearmost pellets may follow the pellets in the front through the target, depending on the distance and other factors. As a result, some pellets may enter the target through the same holes.
Don’t assume that because your shotgun patterns densely at 30 yards, the results will be the same at 40. Shot patterns can change unpredictably and aren’t always linearly scalable.
How to Pattern Your Shotgun
The type of shot pattern you need depends on several factors, including the intended range and target type.
To test your shotgun and its spreading pattern, you should start by attaching a sheet of brown or white wrapping paper to a target stand on a firing range. You should be able to buy a suitable roll or sheet from a printing shop or hardware store.
Choose a sheet that is suitably wide for this purpose—at least 36”. Always ensure that the berm/backstop is solid and can stop ammunition from passing through.
Using a felt-tip marker, write relevant information on a corner of the sheet. This should include the gun, the ammunition type and load—i.e., shot size, number of pellets or shot weight, brand, etc.—the type of choke tube or choke adjustment setting, and the range at which you’re shooting.
The range should be 40 yards for 12- and 20-gauge shotguns; 25 yards for .410-bore shotguns, reflecting the lighter payloads used by such weapons. If you’re using a double-barreled shotgun, specify which barrel you’re using on the paper. Using the same marker, draw a circle on the sheet of wrapping paper as a reference point (if you need to).
Aim at the target and fire a single round of ammunition at the center of the circle you’ve drawn. Find the approximate center of your shot pattern and mark it. This should be the densest part of the pattern.
Insert a thumbtack into the target at the center of the pattern and, using a length of string or paracord attached to the thumbtack, draw a 30” circle. Count how many shot pellets struck the target inside the circle.
To achieve an average, you should fire a minimum of five shotshells. Once you’ve determined the average for this load and choke tube, you can change or adjust the choke tube and try again.
It’s important to remember that you’ll need to experiment to find the best combination of choke tube and shotgun shell load. There’s no set formula for finding this information.
Also, bear in mind that some choke tubes are suitable for steel shot and others aren’t. Check the manufacturer’s instructions when using choke tubes.
Do You Need to Pattern?
While it’s important to ask what distance should be used to pattern a shotgun, you should also determine how and whether you need to pattern your shotgun in the first place.
If, for example, your sole interest in shotguns is limited to home defense, the spreading pattern that occurs due to the use of a cylinder-bore barrel and #00 buckshot rounds may be sufficient.
You don’t necessarily need to install a choke tube or determine the size of the spreading pattern at 40 yards, especially when you may only use your shotgun at distances under 10. You should, however, practice with your shotgun to see how it spreads at closer ranges with your ammunition of choice.
Patterning your shotgun is standard practice for hunting and sport-shooting shotguns firing birdshot or buckshot. If you only intend to use your shotgun for close-range home defense, the patterning of your shotgun may not be relevant or urgent.
However, regardless of whether you intend to adjust the pattern of your home-defense shotgun, you should still determine exactly how it patterns to know where to hold.