If you're newer to the hunting world, then the gear and options can oftentimes be overwhelming. Aside from differentiating between what type of firearm to use, you also have a wide variety of ammo to choose from as well.
The type of ammo you choose is a very important choice and sometimes reading a shotshell box is confusing. Below each number is explained...
When looking at a box of shotshells, usually the first number on the box identifies the gauge of the shells. Gauge is a measurement of the diameter of the shell case. The shotgun gauges manufactured today are: 10, 12, 16, 20, 28 and .410. The larger the number, the smaller the shell diameter. The gauge of the ammunition must match the gauge of the shotgun. If you are unsure what gauge the gun is, check on the shotgun barrel - it should say what gauge it is as well as other specs of the gun. Never place a smaller gauge shell in a larger gauge shotgun. It will appear to fit just fine, but the smaller shell can get stuck in the barrel. If a correctly-sized shell is then placed in the shotgun and fired, an extremely dangerous barrel rupture will occur. To be on the safe side, only carry ammunition that matches the shotgun you are using.
The second number found on the box is the length of the shell. This is normally measured in inches. Most shotguns are chambered for 2¾-inch or 3-inch shells, with some guns being chambered at 3½ inches. Check your gun barrel or owner’s manual to verify what maximum shell length your gun will accommodate. 3½ shells are most commonly used with larger birds like Canadian Geese and some Turkeys.
Next listed is the velocity. This tells you how fast the shot leaves the muzzle and is usually specified in feet per second (fps). Velocities may range from 1,100 fps to near 1,400 fps. The higher the fps, the faster the shot travels.
The last number is usually the shot size. Shot refers to the pellets, projectiles, inside a shotgun shell. Shot is categorized with an inverse naming system -- smaller-sized shot carry a larger number. Though there are smaller shot sizes on the market, #8 is the smallest shot commonly used by hunters. It is used effectively for dove and quail hunters.
The numbering system for shot continues up to #1 shot, commonly used for ducks and geese, and then it gets weird and confusing. The next larger shot is called B shot, which is slightly bigger than #1 shot. BB shot is a little bigger and BBB shot is a little bit bigger than that.
Below is a general overview of shot size, with information about the game each should be used for:
#8, #7 ½: Doves, quail, pigeons, woodcock, small shoreline birds such as rail and snipe:
#7 ½: Hungarian partridge, spruce grouse, blue grouse, and short-range upland birds, such as ruffed grouse and woodcock.
#7 ½, #6: Squirrel, rabbit, hare, short range pheasant, long-range grouse, chukar.
#6, #4: Long range pheasant, long-range chukar.
Non-Toxic Shot: Steel, Tungsten, Bismuth
#4, #3, #2: short-range ducks.
#2, #1, BB: long-range ducks.
BB, BBB: short range geese.
BBB, T: Long-range geese.
#4, #5, #6: turkey.
Lead vs. Nontoxic Shot
For upland birds and small furred game, most hunters consider lead as the go-to material for shot. It’s heavy and soft and it drops game very efficiently. However, lead shot is illegal for hunting waterfowl, and for good reason. Ducks and geese will both purposely and inadvertently consume spent pellets while feeding. This can cause lead poisoning. Therefore, what’s known as non-toxic shot is federally mandated for all waterfowl hunting.
Steel is the most common form of non-toxic shot, though it’s lighter and harder than lead and does not work as effectively in side-by-side comparisons. Other non-toxic materials include bismuth and tungsten, which are heavier than steel and are more comparable to lead shot. However, these metals are more expensive than steel, and also harder. They require a thicker wad to protect the shotgun’s barrel from damage, which results in less room for pellets within the shot shell.