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.