Rifles fire single projectiles. Shotguns fire dozens to hundreds of loose pellets. Unless you’re one heck of a great shot, you’ll hit moving game with a shotgun much better than with a rifle because all those pellets spread out to create an “impact circle” of about 30 inches. Besides, it’s against the law to shoot flying birds with a rifle!
Shotgun pellets, commonly called “shot,” spread because no round pellet is perfectly round. Imperfections on each surface catch the air, so pellets plane and deflect in the wind. Because they’re launched at somewhere between 1,100 feet per second and 1,700 fps., there’s a lot of headwind to mess things up.
Throughout shotgunning history shooters have tried to keep pellets together in a “tighter pattern.” This enabled them to take birds farther downrange. In the old days, a charge of shot was lucky to remain effective to 25 yards. After that the pellets had spread so far apart that many birds could fly between them.
Eventually, gun makers figured out that some kind of restriction or “choke” near the muzzle “squeezed” the pile of pellets enough that they’d stay together as an effective group to 30-, 35-, 40-, sometimes even 50 yards. These chokes became standardized as cylinder (no choking,) improved cylinder, modified, and full. There are steps in between, but these are the major chokes sold in hunting shotguns today. Originally the choke was built into each barrel. Now we have screw-in chokes so you can change to match hunting conditions.
Something else that changes shot pattern density at all distances is pellet hardness. The harder the pellet, the smoother and more consistently round it should be and remain after firing. When a stack of pellets within a shotshell are suddenly launched, they suffer significant G-forces, which squashes them together. Soft pellets get flattened. Hard pellets, less flattened. This is one advantage of steel shot over lead shot. It resists deformation. But it suffers from something else that hurts downrange performance. Insufficient mass.
The lighter any pellet, the faster it slows due to air drag. Tiny pellets lose penetration energy quickly beyond 25 yards. Larger pellets maintain it. Material density also contributes. Because steel shot is light (has relatively low specific gravity or mass) it loses velocity and energy quickly. Lead is more dense, so it carries energy farther. But it’s softer, thus deforms more and blow open patterns. (Compromises, compromises.) Some exotic shot, such as Hevi-Shot shot, is even more dense than lead, so it really reaches out. But it’s expensive, too.
Shotgun Wads Protect Shot
Another way to combat pellet deformation is with wads. A shotshell wad is a plastic “shell within a shell.” It does at least four things.
1. It isolates the shot from the powder;
2. It protects the shot from scraping against the barrel walls;
3. It cushions the shot upon ignition, absorbing some of the shock to reduce mashing under G forces, and;
4. It holds the charge together after leaving the muzzle to increase pattern density downrange.
Some wads do this better than others, which is one of the major differences between brands and types of ammunition.
Given the right choke, shell, wad, and type of pellets, any gauge shotgun can maintain tight patterns equally far downrange. So, a 20-gauge can pattern as tightly as a 12-gauge. But a 12-gauge will remain effective much farther (say 15- to 20 yards) downrange simply because it starts out with a larger payload. A 3-inch, 12-gauge can throw 264 No. 4 steel pellets; a 3-inch, 20-gauge can spit only 192 No. 4 pellets. Advantage, 12 gauge.
Different guns and chokes will handle different shotshell loads differently. This is why serious shooters are urged to test pattern consistently by shooting into large (3-foot x 3-foot feet) sheets of paper or cardboard at hunting ranges (25- to 50 yards) to check for pattern density and consistency. Buy the ammo that performs best in your gun.
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Ron Spomer has been photographing and writing about the outdoors for nearly four decades. He’s written seven books, hunted on six continents and been published in more than 120 magazines. He’s currently rifles’ editor at “Sporting Classics,” Travel columnist at “Sports Afield,” Field Editor at “American Hunter” and “Guns & Ammo” — Optics Columnist at “North American Hunter,” Contributing Editor at “Successful Hunter,” Senior Writer at “Gun Hunter,” and TV host of “Winchester World of Whitetail.” He will write on Shooting Tips weekly for sportsmansguide.com. You can read his blogs and catch some of his YouTube videos at www.Ronspomeroutdoors.com.