Prepper's Armory: Shot Sizes

It's been a while since my articles on shotguns and shotgun chokes, but a question came up elsewhere regarding optimal shot sizes for different purposes. As I mentioned in those previous posts, shotgun bore size is measured in gauge, which is the number of lead balls the diameter of the bore that total one pound. Therefore, it would take twelve balls of .727 caliber to be a 12 gauge, whereas 20 gauge would take twenty balls of 0.617 caliber. 

Caliber and Gauge Chart

Shot sizes use a different numbering system, but just as with gauge, the number goes down as the pellet size goes up. This means that #4 shot pellets are larger than #9, and so forth. 

Shot types are grouped into two main categories, generally referred to as Birdshot and Buckshot. In addition, there are some differences in numbering systems between American, British, and European sizes. As most of our readers are American, and that's the system I'm most familiar with, I'll stick with that one for this post.

Shot Size Chart

Materials

Since shot size effects the number of pellets that fit in a shell, lead is still king when it comes to economics by giving the most bang for the buck, both figuratively and literally. However, in the United States legislation has been passed limiting the use of lead shot in certain areas and for certain types of hunting. In those situations where such regulations are in effect, steel shot is frequently used. Being lighter than traditional lead pellets, it's generally suggested to use steel shot one or two sizes larger than the equivalent lead shot. While slightly more expensive than lead, steel shot isn't prohibitively so.

Another option is shot made of an alloy of bismuth. It's softer than steel (in fact, nearly as soft as lead), but only slightly denser than steel. This makes bismuth safer for older shotguns where steel pellets might damage the barrel. However, bismuth is also more expensive than lead and steel, sometimes considerably so, which limits its popularity on the market.

The latest addition to the shot pellet material menu is various alloys of tungsten. Half again as dense as lead and over twice as dense as steel, tungsten has excellent performance on game. However, tungsten is considerably harder than lead, with some alloys even harder than steel shot, which may damage older barrels. As you would expect, tungsten shotgun shells are also the most expensive option. 

Which Size to Use?

When choosing a shot size, most references are based on lead shot. If steel or bismuth are used instead, simply slide up one or two sizes larger on the chart to find the appropriate pellet size. No change is necessary for tungsten.

Shot Sizes for Hunting

When using a shotgun to hunt small game in the air and on the ground, or for shooting skeet, trap, or sporting clays, smaller pellets give the best combination of shot pattern and terminal effect within their range. For example, #5 and #6 shot are preferred for hunting rabbit, while #7, #7½, and #8 shot are generally considered most effective when hunting squirrel. When overland bird hunting, such as grouse and quail, the preference is for #3 and #4 size shot for larger game birds and #5 and #6 for smaller ones.

Waterfowl hunting has an added complication with federal regulations requiring the use of what's referred to as nontoxic shot. According to some studies, lead pellets from missed shots are believed to have significant health effects on birds when ingested, so a ban on the use of lead shot for hunting waterfowl  became nationwide in 1991. According to the law, waterfowl are defined as the family Anatidae (ducks, geese, and swans) and coots. Nontoxic shot is defined as "any shot type that does not cause sickness and death when ingested by migratory birds", which generally means steel, bismuth, and tungsten pellets.

Many locations have restrictions on using buckshot for hunting large game, such as deer and similar animals, so slugs are most commonly used for that purpose. However, buckshot is still the primary choice for defensive shotgun loads. #4, #1, and #00 buckshot are the most commonly found loads in commercial shells, offering a good variety of pellet size to payload options.

Shot sizes

 

Patterning

When using shells loaded with multiple pellets, whether birdshot or buckshot, the chosen load needs to be patterned, a method of testing to make sure the density of pellets is sufficient for the purpose intended. This process is well understood and involves shooting at the center of a large target at a specific range based on intended use (such as a four foot square at 40 yards for certain hunting loads), then counting pellet hit percentages while keeping an eye out for voids in the pattern. Here's one reference, and another, on the procedure of patterning a shotgun.

Hopefully this post helps make sense of a large, and often confusing, field of information. Good luck, and safe shooting.