I just learned a thing

Posted by Interesting_Extent19@reddit | Firearms | View on Reddit | 19 comments

This is gonna sound stupid to a lot of people but I just learned that the grain on a bullet is about how much the projectile weighs, not the amount of grains of powder. I know it sounds stupid but I was so confused at why my boxes of 115 said they were faster than my 124 grain 9mm and now I get why. Question now is why do we use a stupid metric for measuring bullets? And 11t grains of what? Are we using sand as the standard or something?

[-]

BlindMan404@reddit

You have the entire fucking Internet at your fingertips and you didn't bother to just look up the answer to your question.

It would take less than a minute for you to answer it yourself.

[-]

Ok-Return7750@reddit

The big question is - why is the firearms industry such a mish mash of Metric and Imperial ??

For example we have 5.56 x 45 mm cartridges but the bullets are measured as 55 to 72 grains.

Then there’s .223 which is Imperial.

Has the whole world gone topsy turvy ??

[-]

TacTurtle@reddit

Old cartridges vs modern and foreign vs domestic mostly.

[-]

DumbNTough@reddit

Because some cartridges originated in Imperial countries and others in metric countries, brudda.

Also some places that are all metric also list or convert bullet weights to grams.

[-]

Accurate_Reporter252@reddit

5.56mm NATO's "maiden name" was .222 Remington Special.

7.62mm NATO was derived from .300 Savage but sold as .308 Winchester before adoption.

7.62×54mmR was originally "3-line rifle cartridge" and not metric.

You can argue that many French and German rounds were from imperial metric countries as they had Emperors or Kaisers or Kings after the US got rid of theirs. The Brits still have a King and a metric system, but still named cartridges under the older systems before using metric system too.

Then there's things like .380 ACP/9mm Kurz which were designed at the same time, named two different things at the same time depending on where the gun was being sold/made (US as the .380 ACP, Belgium as the 9mm Kurz).

Basically, the name of the cartridge usually depends on who standardizes it and when.

[-]

Accurate_Reporter252@reddit

First, you're dealing with something that--if you screw it up--is involved in the routine detonation of small explosions adjacent to your head and face intermingled with engineers, government contracts, and a bunch of arcane legal requirements.

So, when you look at it from that perspective, innovation (in terminology) is moderated by a rather conservative infrastructure and process.

Think about it like this...

One of the most common calibers for civilian and some police and military weapons is the 12-guage shotgun.

12-gauge is a bore diameter that is based on the size of a perfectly spherical ball of lead made form 1/12 of a pound of lead...

That predates fractions of inches, metric, and everything else in many ways.

Why is it that way?

It's because of the ongoing use of a caliber and shell design based on continuous use and manufacture of weapons in this caliber and ammunition in this caliber for personal, commercial, civil, police, and military use for well over a century... and the needs to clearly communicate between all of these people and legal structures exactly what they're getting before they set off the small explosion right in front of their face...

For 5.56mm x 45mm... that's a military standard--especially NATO--for a family of cartridges derived from a commercial standard cartridge (.223 Remington, original .222 Remington Special) to differentiate it--for safety's sake--from an earlier, related cartridge (.222 Remington Magnum and .222 Remington) although 2 separate loading standards and chamber specifications exist (.223 Remington in commercial standard and 5.56mm NATO military standard) and a hybrid version called .223 Wylde which isn't a real caliber, but is a chamber specification to safely use both 5.56mm NATO and .223 Remington commercial rounds in the same chamber without overpressure issues or inaccuracy.

Oh, and there's a family of bullets being used...

Quick, now ask me about Navy caliber/.357 Magnum connections or Army caliber through to .44 Magnum...

[-]

TacTurtle@reddit

grains avoirdupois comes from apothecary / medicine, as those were the first major uses of saltpetre, sulfur, etc before modern chemistry as a separate science came about. The first makers of gunpowder were the same apothecaries, and their traditional weights were retained in use making gunpowder as they were small and accurate enough to be relevant for establishing charge weight.

Metric and the use of the gram for measuring weight came literal centuries later (1795), well after the custom of using grains for firearm powder had been firmly established.

[-]

tatertrap@reddit

Not knowing something isn't stupid my friend. It's one of my favorite things about firearms, there's always not to lean. It's actually ironic, in the US caliber used to be the diameter of the bullet in inches, and the powder charge. .45-70 is a .45 inch diameter bullet over 70 grains of black powder. One of the last cartridges measured like that was .30-30. One of the first US rounds to use smokeless powder. After the advent of smokeless powder they moved away from that. Metric measurements don't tell you anything about the powder. That's why a 9x19mm can have the same bullet weight, and deferent velocities. You'll see +p ratings on some cartridges and that means it's loaded with more charge than standard, but it doesn't specifically say how much. Before you for +p ammo, check the book to make sure it's safe to do so (it usually is, but still check). You look cool at the range until the darn thing blows up in your hand.

[-]

Accurate_Reporter252@reddit

Both the bullet weight and the powder weight are in grains...

That would be why part of the confusion, by the way.

[-]

TpointOh@reddit

Actually, both the bullet weight and powder charge are measured in grains. It’s a holdover from the era of black powder, where that was the standard imperial unit. Whether good or bad, imperial units ended up used by a lot of countries, and continue to be a standard even when other units come to be. It’s a similar situation to “bore” and “gauge” as used for muskets/rifles and shotguns. It’s something like the size of the barrel matches the diameter of a ball of lead that is x fraction one pound of lead. So, 12 gauge is 1/12 of a pound of lead, formed in a ball, and that decides the diameter of the barrel. There’s a lot of weird things like that in the gun industry

[-]

kwb166@reddit

Imagine having no idea that Google exists...

https://www.google.com/search?ie=UTF-8&client=ms-android-att-us&source=android-browser&q=bullet+weight+in+grains

[-]

tdavis20050@reddit

I prefer this format https://letmegooglethat.com/?q=bullet+weight+in+grains

[-]

Interesting_Extent19@reddit (OP)

Thats the one. I normally go to firefox to get to letmegooglethat.com Its amazing how much Firefox can do in 2026

[-]

alkatori@reddit

1 grain \~= 65 milligrams

It's just a US customary unit rather than a metric one.

[-]

maxgaap@reddit

The grain was the legal foundation of traditional English weight systems,[and is the only unit that is equal throughout the troy, avoirdupois, and apothecaries' systems of mass.

[-]

Interesting_Extent19@reddit (OP)

Thats interesting. I didnt know that grain was so universal. You learn something new ever day

[-]