What Does Grain Mean in Ammo?
Gather ‘round: It’s time for some a bit of educational storytelling — for history and science to help explain a commonly used term in the shooting world. Now, I know what you’re thinking: "I just want a simple answer to the question. I don’t need the school lessons."
What does grain mean when you're talking about ammo?
We could give you the quick, simple answer and tell you it refers to the weight of the ammunition. Question answered and job done. But is it really?
There are two problems with such a simple answer. First, where’s the fun in it? Second, and probably more importantly, it doesn’t really give you a good understanding of how the concept applies to your shooting.
At Ammunition Depot, we're firm believers in the idea that the more you know about firearms and the better you understand them, the more effective you can be when using them. All firearms-related knowledge helps you become a better shooter. Okay, maybe not everything. Certainly, knowing Eugene Stoner’s birthday won't help you shoot your AR better, but you get the picture.
(It’s November 22nd, by the way.)
Since our goal is to build your knowledge base and help you become a more well-rounded firearms owner, you'll find a more in-depth discussion of what grain means below.
What Is a Grain?
In simplest terms, grain is a unit of measure. It's one of the smallest units for measuring weight. Since ammunition and its component pieces are quite small, it's common to find the weights of things related to ammunition measured in grains.
For centuries, a grain has been the smallest unit of measure in common usage. Yes, there are varying other smaller weights used to measure things, but grain is one that goes back the farthest. In fact, grain is an ancient unit of measure and is consistent across the three main weight measurement systems — the avoirdupois, troy and apothecaries’ systems. Oh yeah, now we’re really learning.
How Much Is a Grain?
A grain is equivalent to 0.065 grams, or 1/7000 of a pound. It would take more than 400 grains to make just 1 ounce. There are more ways that it could be compared, but you understand what we’re getting at: This unit of measure is quite small. So small, in fact, that the unofficial scientific term for it is teeny-tiny.
Given that it’s such a small measure, grain can be very useful when weighing bullets, shell casings and even powder. But we’ll get to more on that in a minute.
Why Is it Called Grain?
The unit of measurement derives its name from the fact that it was used when weighing things in ancient markets. In ancient times, merchants would take a specified amount of a grain (such as dried wheat) and use that to weigh things that were being purchased. This actually became such a common practice that other things were standardized according to the grain measurement.
Grains were selected from the center of the ear of whatever grain plant was being used and then compared as a reference for the thing that needed measuring. The ancient Sumerian shekel was equal to 180 wheat grains, for example. In fact, the first part of the word shekel, she, is representative of the wheat grains used for the measurement.
What’s It Used For?
We’ve discussed that grain is used as a measure for weight, sure. But what is it used for with regard to firearms? Typically, it’s used for bullets. You wouldn't find someone talking about the weight of their entire rifle in grains.
As a quick aside here, notice we said bullets. You typically will only see grain as a unit of measure for cartridges that contain a bullet of some kind. Standard shotgun shells won’t usually have a grain listed, but a measurement of the total shot weight in ounces as shotshell loads are generally way heavier than bullets. It’s all about letting you know the weight of the projectile or payload coming out of the barrel.
Grain can actually be used to measure the weight of every component of the round, but it’s mostly used to describe the weight of the projectile itself or the powder for people who load cartridges by hand. Because of this, many people will sometimes mistakenly believe that when they see the word grain on ammunition that it’s speaking of the powder. It isn’t. When you see an indication of grain on a box of ammo or the stamp on the base of a casing, it’s talking about the weight of the projectile.
Is Grain Important?
Yes and no. There are certain ballistic features and characteristics that change depending on the weight of the round. Getting one that’s a little heavier or a little lighter might well be something you need to do in certain circumstances.
Take, for example, shooting with a suppressor. Suppressors work by deadening the sound of the explosion and the gasses. However, the round still makes the crack of the sonic boom as it breaks the sound barrier flying through the air. With a round that’s a heavy enough grain, it won’t quite reach a speed fast enough to do that, and the sound profile will be reduced even further. This kind of ammunition is referred to as subsonic ammunition, and while it isn’t a requirement for shooting suppressed, it's a good idea.
Additionally, some guns tend to naturally “prefer” rounds of a certain grain weight. Some of them don’t function right without certain grain ammo. Most types of guns can handle almost any ammunition you throw at them, but others won’t cycle properly if you try to shoot something that’s too heavy or too light.
So yes, the grain matters. But really it depends on the gun and the need you bought the ammo to fill.
There, isn’t science fun? It’s not so bad learning a little history either, is it? Especially when it can help you understand an element of firearms that is often misunderstood. While this isn’t an exhaustive, all-encompassing primer on everything related to grain, it’s still plenty of information that should help you better understand the rounds you’re buying. And that helps you make more informed decisions when purchasing — making the right purchase can help you in your shooting.
And that’s what it really all comes down to: Shooting, and shooting well.