Shot sizes are one of most confusing aspects
of the shotgun world. For newcomers, all those arbitrary letters and numbers are an utter
mystery; and even many experienced shooters can’t keep track of all the different sizes,
their diameters, and how they’re organized. And every shot size chart or table I’ve
come across is incomplete in one way or another. So I figured I’d kick off this new video
series with an exhaustive, two-part video guide that covers all of the American shot
sizes, common and uncommon. I’ll explain the various formulas and naming conventions,
and touch briefly on what the different sizes are used for.
I’ll explain some basics and try to keep things easy for newcomers to follow, but even
experienced shooters should be able to learn something new here.
Now, the American shot size system isn’t the only one in the world, but trying to include
others in the same video would just be confusing - especially with birdshot, where the same
numbers and letters refer to different diameters in different systems.
A majority of my viewers live in areas that predominately use American shot sizes, so
that’s what I’ll cover first. Other shot size systems will get their own videos later
on. I’ll get to specific sizes shortly, but
first, some definitions and background: For the purposes of this video, shot refers
to spherical projectiles fired two or more at a time from a firearm. Shot size is either
the nominal diameter of the pellets, or the standardized name representing that diameter.
Non-spherical shot exists, but I’ve never come across a standard size system for those
projectiles, and they only show up in a handful of novelty or specialty shotshells anyway.
Shot can be made from a variety of materials, but I won’t get into that much in this video
because standard shot sizes are the same for all materials. Despite some misleading charts,
there aren’t separate size systems for lead and steel shot.
As used in firearms, shot can be separated into two major varieties: smaller birdshot,
and larger buckshot. Both are round pellets fired manifoldly, but they can be distinguished
by their size, the way they’re loaded, their ballistic properties, and how they’re used.
The next video will cover buckshot; this video will focus on birdshot.
Birdshot is very much the characteristic shotgun payload. Dozens, hundreds, even thousands
of birdshot pellets are fired simultaneously, and spread out in flight to create a wide
cloud - called a pattern - that improves the shooter’s chances of hitting small, fast-moving,
and/or distant targets. The idea is that with the right pattern; a
target anywhere inside will be hit by enough pellets to get the job done.
This is the kind of behavior most folks associate with shotguns - sometimes incorrectly so,
but more on that in the next video. As the name suggests, birdshot is used on
all types of birds, along with other small game animals, pests, and varmints; and inanimate
objects like the breakable clay discs used in various shooting activities.
Because birdshot pellets are relatively small and used in large numbers, the amount of birdshot
in a shell is typically described by the total weight or mass of shot, usually in ounces
or grams. When it’s loaded, the shot is measured out by weight or an equivalent volume,
not by a specific number of pellets. Ammo manufacturers may give pellet counts
in addition to the weight of shot, but these numbers are almost always estimates.
Standard American birdshot ranges from the size of a grain of sand to just below the
smallest buckshot in steps of one hundredth of an inch. There are also accepted half-sizes
that cut that step to just five thousandths of an inch.
That’s less than the thickness of one of my beard hairs.
All these birdshot sizes are split between two major naming systems. The smaller sizes
use a system of numbers, while larger sizes are designated by letters. We’ll run through
the sizes, starting at the bottom with the numbered birdshot.
The way these numbers work, the lower the number, the larger the pellet. It’s a little
counterintuitive, but there’s a handy mathematical formula that relates these numbers to their
corresponding pellet diameter. Simply take the shot size number, subtract
it from seventeen, and the difference is the nominal pellet diameter in hundredths of an
inch. Take #5 birdshot as an example. 17 minus 5
is 12. Move the decimal point two places to the left, and #5 birdshot pellets are .12
inches in diameter. This formula also holds true for non-integer
numbers, allowing for half sizes such as 7½. 17 minus 7.5 is 9.5, or .095 inches. The numbered birdshot sizes start at #12, which is .05 inches in diameter, followed
by #11, and #10. Anything smaller than #12 is simply called “dust shot”, though sometimes
#11 and #12 are also referred to as dust shot. Because of their very low mass, tiny #10,
11, and 12 pellets are only effective on small animals at very close ranges. For that reason,
these sizes are used primarily for pest control, and are often called rat-shot or snake-shot.
You won’t see many actual shotgun shells factory-loaded with this tiny shot nowadays;
but it does show up in specialty shotshells and pistol cartridges, and the shot by itself
can be obtained for handloading. Moving up the scale, we have #9, 8, and 7
shot. Unlike minuscule #10 and smaller sizes, this
shot is heavy enough to remain effective beyond absolute point-blank ranges, but still provides
very high pellet counts and large, dense patterns that are ideal for fragile, but small or fast-moving
targets such as clays or small game animals. Also in this range are #7 ½ and #8 ½ birdshot.
These are the only common half-sizes in the American system, though others can be defined.
When dealing with pellets this small, half-sizes offer relatively significant changes in pellet
count, and with the way these sizes are made and used, it makes sense to have these intermediaries.
Since #9 through #7 lead birdshot is less expensive to manufacture than most larger
sizes, they’re what you’ll usually find in cheap, steel-based, bulk-pack shotshells
that are great for inexpensive plinking and training.
Next, #6, #5, and #4 birdshot are popular for hunting most upland game, as well as smaller
or close-range waterfowl. .125” #4 ½ shot isn’t unheard of. Some
reloading suppliers offer slightly oversized #4 shot that’s technically #4 ½. And since
that’s exactly one-eighth of an inch, metal balls from various other sources can be repurposed
as shot. But if you see shotgun ammunition specifically
marked as #4 ½ birdshot - or 5 ½, or 6 ½ - you’re more likely dealing with a different
shot size system. British birdshot sizes include #4 ½, but that’s similar to American #6.
Above #4 is #3, #2, and #1 birdshot. These bigger pellets are used primarily on waterfowl;
offering the penetration and energy retention needed for big, tough birds like geese, or
long-range shots at high-flying game. At .16 inches in diameter, #1 shot tops off
the numbered birdshot sizes. Larger sizes still move up in hundredth-inch increments,
but the math is replaced by a new system of letters and tuples.
The sizes just above #1 are the “B”s. At .17 inches – what would have been #0
by the number-size formula - is B shot. After that, we have BB shot at .18 inches, and triple-B
at .19 inches. If that middle one rings a bell, yes, .18-caliber
BB birdshot was the original basis for the name and bore size of BB air guns. However,
air rifles have evolved some since their introduction, and the standard pellet size for modern BB
guns is 4.5 mm, or .177-caliber. Also, it’s worth mentioning that “BB”
is often used as a catch-all term for shotgun pellets. If someone uses "BB" as a plural
noun, as in “I like magnum shells because they hold more BBs”, they probably just
mean pellets in general, not necessarily BB-size pellets.
Anyway, above triple-B, there’s no quadruple-B. Instead, things start over with a new letter,
and we have .20-caliber T shot and .21-caliber TT shot. Then, the letter changes once more
to give us .22-caliber F shot – sometimes called triple-T – and .23-caliber FF shot.
The “B’s” and “T’s” are common steel shot sizes for waterfowl hunting in
areas where lead has been banned. Since steel shot has a relatively low density, achieving
the same penetration and effective range requires larger pellets.
The biggest “T” and “F” birdshot sizes are also used on thin-skinned varmints and
predators like coyotes and wild cats. Compared to buckshot, these sizes offer higher pellet
counts at the expense of some range and penetration. There’s no handy formula for these letter
birdshot sizes, but they’re not too tough to keep track of. Just remember that “B”
shot is essentially #0 at .17-caliber, then the other two “B”s, the “T”s, and
the “F”s follow in the usual hundredth-inch increments.
The “F” sizes top off the American birdshot system. One hundredth of an inch above FF
is the smallest buckshot size, .24-caliber #4 buck. We’ll start there next time.
All in all, American birdshot isn’t too difficult to grasp and remember once you see
how the system works. Stay tuned for part 2 on buckshot, where things get somewhat less
straightforward. For now, I welcome any questions and comments,
and please let me know if there are any general shotgun topics you’d like me to explain.
I’ve been planning this new video series for a while, and now that it’s finally off
the ground, I’m looking forward to feedback. Until next time, have fun and shoot safe.
