If mm doesn't refer to the length or width of a bullet or the barrel, wtf does it refer to then?
If mm doesn't refer to the length or width of a bullet or the barrel, wtf does it refer to then?
If mm doesn't refer to the length or width of a bullet or the barrel, wtf does it refer to then?
It's the length of your penis.
How high are you anon?
I heard that mm doesn't refer to either the size of the bullet or barrel
And you believed it?
I don't know anything about weapons, being an Australian /m/gay, the absolute furthest from a /k/gay you can get.
Well then frick off ya homosexual c**t
Fellow ausgay here.
The leading number is bullet diameter. The following number is case length.
Now go get a firearms license for sport shooting in class A and B, and buy a rifle.
>The following number is case length.
It surprised me while back that it overall bullet length
If you think about the mechanics of what's happening, the length of the bullet doesn't matter. Who cares where the explosion pushes? Overall length would be a slightly more useful second figure but it would be misleading in a lot of cases; some bullets are long and pointy, others are perfectly flat faced, some have a hollow base, etc. As long as the cartridge isn't too long to travel through the innards of the gun, it doesn't matter much.
>the length of the bullet doesn't matter.
What is head spacing? And how does it affect things like accuracy, brass rupture, out of battery firing?
"bullet" doesn't mean "cartridge" anon.
>What is head spacing
Something that is unrelated to bullet length.
9mm is named as such because the width is 9mm.
The mm refers to is either the casing, projectile or the whole bullet.
This question actually touches on a much bigger one:
"How do we name things?"
Like the bullet obviously doesn't have a "name" the ...shape? of it does. The same caliber might be made by different companies.
You're referring to it somehow by using it's properties. It's entirely arbitrary which properties you use, what's important is if others (preferably manufacturers and Logistics officers) can communicate "what bullet IS it"?
that beings said. This is now a bullets naming thread.
50BMG = The Beef, Pricks, Mules, "Kherberos"
7.62x39 = The Red, Chekovs, Sojuz, "Polis"
5.56 x 45mm NATO = The Free, Peas, Nah, "Athena"
.308 Winchester = The Boys, Boomers, Nams, "Charon"
cringemeister of the week.
here the prize you may receive crown and scepter later.
No. It's the diameter of the barrel, measured from either the lands or the grooves (the most obvious example is that 8mm Mauser is 8mm from the grooves and 7.92mm from the lands.)
Bro just type that into Google instead of 4chin and you won't publicly humiliate yourself
Okay not OP but maybe someone can explain pic related, many such cases. How does ammo end up with a slightly different diameter than it's name?
because .38 caliber traditionally used a .357 diameter bullet in a .38 inch diameter barrel. actually most firearms use a bullet that is a different diameter than the barrel bore, but the .38/.357 is a particularly instructive example.
>but why
muzzleloading black powder rifles used a patched bullet. the difference in diameter was made up by the patch wrapped around the bullet. Once they went to cartridges and no longer needed patches then manufacturers kept the bullet diameter and shrank the barrel diameter to match.
>but why didn't they rename them to .357
at the time of the transition everybody knew that a .38 caliber weapon used a .357 caliber bullet, because that's what they'd been shooting their entire lives, so there was no reason - it would have actually been more confusing. decades later that was no longer the case, so when the .38 special was turned into a magnum, the new cartridge was named the .357 magnum reflecting the actual bullet diameter.
Interesting. Reminds me of how surviving writings don't talk about the actual tactics used by the Roman legions. We know the results of battles, and some rough ideas about strategies, but have to extrapolate what actually happened when they were fighting face to face/shield to shield. Because why would somebody bother to write about something that everybody knows?
I always figured it was because of cartridge conversion cylinders. if you had a .38 cap and ball revolver and bored the cylinder through to fit metallic cartridges, the cartridge would only have as much room as the bullet diameter which necessitated heeled bullets. once you got past that shit they just put smaller bullets in the same case size but kept the name the same for a while.
>because .38 caliber traditionally used a .357 diameter bullet in a .38 inch diameter barrel.
No, the original .38 bullet was heel-based bullet of .380" diameter with the case crimped around the bottom, like the .22LR round, later the diameter was decreased to .357" with the bullet seated inside the case mouth.
>How does ammo end up with a slightly different diameter than it's name?
There's tons of reasons why that can happen:
-it's deliberately misnamed either to make it sound cooler than it really is for marketing purposes (i.e. .480 Ruger is a weaker version of the .475 Linebaugh, but calling it .480 instead makes it sound like it's better) or simply to avoid confusion with some other cartridge.
-Different countries have different traditions when it comes to the measurements. Some use groove diameter while others use the land diameter.
-It could be the result of a historical change. For example, in the days of the old west ".44" caliber guns had heeled bullets and both the brass and the bullet had that same diameter. When things got modernized and the .44 magnum was developed it has the same diameter brass as the old .44s, but it no longer uses a heeled bullet, so the bullet now measures .429 instead, but the name .44 was kept. This kind of thing also happened when paper-patched bullets were used.
The take away from all of this is that when you hear about a new round, you might as well assume the first number in the name is the diameter of the bullet with a bullshit randomization within plus or minus ten percent.
Patching like that one anon said, as well, a lot of old black powder cartridges used heeled bullets that were wider outside the cartridge case than inside of it. The bullet was mushroom shaped.
Later, the heel was cut down so the bullet was 'D' shaped, but the old name stuck.
Millimetres because there are two m's in it. Its not firearms specific. The French and American Armies also use it for bolts and distances between beds and shit like that, like where you fold your toowel
You guys are moronic, mm refers to millimeters, you absolute smoothbrains
Seriously though, take 5.56x45. Both numbers are millimeters. The 5.56 refers to the bore diameter, specifically the distance inbetween lands. The bullet diameter is going to be slightly wider (in this case, 5.7mm), since it is the diameter between grooves. The 45 refers to case length in millimeters
>7.62-06
Checkmate eurogay.
Cartridge names are loosely based on physical dimensions, but only loosely. 22, 222, 223, 224 are all the same physical diameter. So are 357 and 38. Sometimes the cartridge name is an exact dimension, but which dimension? 300 and 308 are the same diameter. 300 is the barrel measurement between lands, 308 is the measurement between grooves.
It depends.
Sometimes it is just a name.
8mm Mauser is not 8mm and the alternative name of 7.92mm Mauser still isn't accurate.
.223 Remington (5.56NATO) is the same size as .222 Remington, but named to distinguish itself.
There are a bunch of others like that.
Most of the time it is a measurement, but sometimes it's just a ballpark approximation, with the name there to differentiate one cartridge from another that is dimensionally similar.
What else would it refer to?
How deep it can penetrate a vatnik's skull
you need to subtract the first number from the second to get the real bullet number
like the full name for the 9 is 9x19mm, so really it's 10mm
Length of your penis.
Multi-Meter
Electrician pilled
Think of them as names. They don't tell you frick all about the power of a cartridge except in a vague sense.
The mm is about the bore diameter. Caliber is roughly about the bore diameter in inches, where .45 = .45 inches, but naming is all fricked. Gauge is even more moronic. It is about the bore diameter relative to the circumference of a spherical pound of lead. A 12 gauge shotgun has the bore diameter of a 1/12th pure lead ball. This is why a 10 gauge is larger, it is 1/10th that size.
Anyhow, it doesn't mean much without knowing the cartridge. 5.56mm NATO is an intermediate cartridge used in many assault rifles and far more powerful than 9mm. But 6.8mm and 7.62mm are more powerful than 5.56mm. .30-06 is larger, and slightly (or a decent amount more if pissing hot) powerful than .308. There are many .50 cal cartridges, which is 12.7mm. there is .50 Smith and Wesson, a round used mostly in gigantic revolvers, which while powerful for a hand gun, isn't more so than a rifle. There is .50 Beowulf for a moronic .50 assault rifles, which is a dumb cartridge. But what most people mean when they say .50 cal or 12.7mm is the Browning Machine Gun round, which is very large and used in anti-material sniper rifles or heavy machine guns.
Larger bullets are effected less by wind and tend to have straighter ballistics if they have enough power behind them. This is why they are ideal for belt feds, because you might only get a short window to hit the adversary as they move between cover, e.g. a chance for traversing fire, but this is harder with 5.56mm because it has rainbow arc ballistics at greater distances. Also, you can generally engage at longer distances with a belt fed anyhow and penetration is more important for the automatic rifleman. But it's too heavy except for mounting in vehicles or setting up in a fixed position.
Soviets and their successors use 14.5mm for heavy machine guns, which is even more powerful. At 15mm+ automatic weapons are "autocannons."
Also, for artillery there isn't a linear relationship between bore diameter and size. Your standard 155mm shell is 43.5kg., while a 203mm shell is over twice the size at 110kg. 203mm isn't used that much anymore because you can just drop bombs, which can get significantly larger.
>for artillery there isn't a linear relationship between bore diameter and size
that's true for any projectile weapon. the volume of the bullet - all other factors being held constant - is proportional to the square of the radius of the bullet. Making the simplifying assumption that the "projectile" is a simple cylinder of 3 calibers, a 155mm version of such a projectile has a volume of 2,792,906 cubic mm, whereas a 205mm version of such a projectile has a volume of 6,461,343 cubic mm - the 205mm projectile has 2.3x the volume of the 105mm one.
it refers to the barrel bore diameter but no matter if it's in mm or caliber (which is inches) it's rarely 'actual' and is often used simply as a designator. For example, .308 cal and 7.62×51mm NATO have identical case and bullet diameters (but different case pressures), however 7.62mm does not convert exactly to 0.308 inches. 0.308 inches is 7.82 mm, which is the actual bullet specification of 7.62 NATO.
Likewise .300 BLK is not actually 0.300 inches in diameter, its bullet is also 0.308 inches in diameter.
Are you over 18?
>MM - Chocolate inside
>Skittle - Candy inside
Lurk b4 posting.