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what does the x39 (in the 7.62x39) and the...
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You are currently reading a thread in /k/ - Weapons

Thread replies: 63
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what does the x39 (in the 7.62x39) and the x45 (in 5.56x45) mean?
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Length of the cartridge.
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What do you think the 7.62 or the 5.56 means??
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>>28643556
how many hit points damage

do you even d&d bro
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>>28643556
Length of the case. Not the entire cartridge
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>>28643570
does it include the bullet or is it just the measurement of the cartridge?

>tfw having 2 7.62x39 rifles and have never actually measured the rounds from end to end
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>>28643556
How many children one cartridge can kill per squeeze.
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>>28643556
>https://en.wikipedia.org/wiki/7.62%C3%9739mm
>Case length 38.70 mm

Learn Google faggot.
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>>28643570

This is incorrect. It means the length of the case.
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>>28643556
39 people killed with every trigger pull
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>>28643639

so a 7.62x39 and 7.62x45 could both be fired from same gun as they are both 7.62's ?
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>>28643969
Wha? No. The bottle necking wouldn't necessarily match the barrel width and could cause seriously bad case expansion.
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>>28643981

Figured as much. Thank you.
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>>28643969
7.62x45 won't headspace in a 7.62x39 chamber, so no
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>>28643556
It's how many baby seals die from the manufacturing process to produce each round. 100 rds = 3900 dead baby seals.
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Im glad someone else was wondering this too. What else should a newfag know about ammo? I own a shotgun but have no experience with pistols, rifles and their ammo.
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>>28644204
Know that surplus ammo (especially 7.62x54r, 7.62x39, 5.45x39) is usually corrosive and it is /k/ recommended to clean your rifle after every use of the stuff.
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>>28644264
>clean after every use
>not cleaning after every shot
its like u haet guns
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>>28644204
9mm is .357 caliber
.38 caliber is actually .357 caliber where .38 special is concerned. 9mm makarov is slightly bigger around then 9mm luger. Same diameter as .380 acp. Acp means automatic colt pistol, colt made a lot of brownings designs in .25 acp, .32 acp, .380 acp and .45 acp. Handgun rounds typically travel at 2 to 2.5x slower then a rifle and have much less energy. Handguns aren't really useful much past 50 yards at the max, best is shotgun distances for handguns.
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>>28644264
>cleaning your guns
>ever
no thanks
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why "caliber" has multiple meanings?
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>>28644329
Caliber is the diameter in inches. .45 is .45 inches or just under half an inch.

Milimeter is the diameter in milimeters. 7.62 is 7 and .62 milimeters in diameter or in caliber that's .30 inches
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>>28644299
Thanks for the info. Could you explain the part about the different calibers like im really stupid? Like if I just came across a random round could I pick it up, look at it and know what it is and what guns I could use it in?
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>>28644399
just look at a lot of pictures of different rounds (or irl) and you will learn to recognize them when you find them, also some have the caliber stamped on the bottom
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>>28644204

r stands for rimmed.

spitzer boolets are pointy

greentip is m855

You can fire a .223 in a 5.56 but not the other way around (although this is less true these days, as most imported guns are labelled .223, but actually spaced for 5.56. Since .223 is a civilian round it's easier to export guns in it or some shit.)

.357, .38, 9mm, are all the same width of bullet. They can all be fired out of the same barrel. They are all 9mm. (however for a revolver you'll need a conversion cylinder to fire 9mm, since the case length is so different, and a semi-auto will only be able to use one of the above because loads of reasons)

the 06 in 30'06 stands for the year it was introduced to the US army. The 70 in 45-70 stands for the grains of black powder the round uses. This is the case for most old rounds, .30-40 krag (although this one refers to smokeless powder), 30-30 (also smokeless), etc. In other words those following numbers have nothing to do with caselength or only have an indirect relationship. It's only when it's an x that it's case length, such as 7.62x39, 5.45x39, etc.

Measurements like 7.62x51 are metric. .308 is the Imperial equivalent. Same goes for 5.56x45/.223. (although in both these cases the rounds are SLIGHTLY different). Also nowadays the imperial designation is the civilian designation. 7.62x51 is military. .308 is civilian.

>>28644399

.380, 9x18, 9x19, .357, .38, all have bullets that measure 9mm in diameter. That is not the only measurement that matters however, there is also case length and thickness and other nonsense, only put rounds in guns chambered for them. Even though a .380 or 9x18 can fit in a regular 9mm pistol, doesn't mean it won't blow up in your face.
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>>28644399
I could... But that's 30 years if experience. On the back of the casing is usually stamped the caliber
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>>28644496
Thats exactly the kind of answer I was looking for. I think I'm starting to understand. Anything else anybody want to add? Ive seen many different looking rounds that must all have different purposes.
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>>28644716
Pointy bullets penetrate better, rounded bullets dump more energy on target. Hollow points expand like crazy and rip into the target but only soft targets. Do jack against armor. There's also a thousand different types of powder for a thousand different loads.
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>>28643556
the x39 and the x45 are the country-codes

x39 is Russia/Soviet-union code

and x45 is the USA country-code

.308 was invented in France, so it's country code is x51
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>>28644824
1/10 bullshit, made me reply
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>>28644716


>Ive seen many different looking rounds that must all have different purposes.
Sure. I'm no expert, but rounds are generally made with a specific purpose in mind. Big round or flat-head bullets like that one there are slow and heavy, meant to fuck shit up by their sheer weight, kinda crushing through shit. They don't work well over long distance, so they're generally used for pistols nowadays. Older ones like .45-70 are used in rifles too, where they're generally relegated to being fucking cool, or hunting.

Little pointy ones are meant to be fast and generally perform well over great distances. Full powered rifle cartridges like this (such as .308, .30'06, 7.62x54) just fuck things up simply by being a big bullet going fast. Intermediate rounds like 5.45 or 5.56 have less sheer force, and so generally have a bullet designed to do something to make up for their lack of inherent 'stopping power'. 5.45 yaws, it flips end over end after impacting, turning the inside of whatever it hits into a meat blender. 5.56 fragments, sending shards of lead and whatever else rocketing through you. 7.62x39 is perhaps the most intermediate of the intermediate calibers, it uses a big bullet like a full powered rifle cartridge, but a smaller case. As such it's less effective over distance, (having less powder behind it but still using a large fairly heavy bullet) but its weight means it can penetrate barriers with its trajectory unaffected, it'll go through a wall and still kill you on the other side, while 5.56 might fragment or lose a lot of momentum. Then there's even smaller ones like 5.7 and 4.6 used in the p90 and mp7 respectively. These are intended for armor piercing, they're little fast needles basically that just punch straight through armor.
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>>28643626

yeah OP, you're wasting thread space where we could be talking about how much we want to shoot black people and liberals.
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Thanks for all the info everyone. I've learned a lot so far. Any difference between the straight wall cases or the ones with a sort of neck? Why not just make the whole case thinner so you can fit more rounds in the mag?
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>>28645424
Also, I started wondering about all this when I saw a thread earlier about custom rounds or something. Lurked a bit and realized that I didnt know shit. There were a lot of terms being used that I didn't understand.
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>>28645424

>Any difference between the straight wall cases or the ones with a sort of neck?
Well yeah. They have a neck.

>Why not just make the whole case thinner so you can fit more rounds in the mag?
Because then you wouldn't be able to fit enough powder in the case.

It's so you can fit the bullet you want in a case that'll hold enough powder basically.
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>>28645424
The neck in the case is to increase the pressure and in doing that it increases the bullet velocity and thus makes the bullet shoot at a flatter trajectory
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Someone had mentioned that there are different types of powders as well. I knew that the powder we use now is different than black powder but what else do I need to know. What else is there and why/what for?
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>>28645857

There's shitloads of different formulas basically. They have different pressures and burn rates and other shit. Not important at all unless you want to get into reloading.
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>>28646081
So basically just a difference in energy? I would like to get into reloading someday.
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>>28646363

Pretty much. Some will perform better with different barrel lengths.
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not OP but loving thread. as for >>28646438 yes ive heard that some bullets have powder that assumes a certain barrel length so the explosion depletes it energy in the space alloted. is there like a calculator or list of formula concerning these things? atf here
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>>28643969
You wouldn't be able to fire both cartridges from the same gun, BUT you could load the same PROJECTILES in each cartridge.

E.g. 7.62x39 and 7.62x51 (308win) are the same projectile weight, although the x39 cartridge fires a lighter weight projectile than the 308win. A typical x39 projectile is like 123gr and a typical 7.62x51/308win projectile is like 168gr.
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>>28646438
Trying to think of how the science behind that would work. Im guessing a faster burning powder would be ideal for shorter barrels and slower powder for longer barrels? I think I've read before that there are different kinds of rifleing, does that make a difference in what casing, powder type/amount or bullet to choose?
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>>28643573
Nothing. It's supposed to be bullet diameter, but it often is not.
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>>28646506
There are some differences between .30 caliber projectiles as well. Small ones that can affect accuracy some. Russian, Japanese, and .303 Brit all use .311-.313 projectiles.
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>>28646506
>7.62x39 and 7.62x51 (308win) are the same projectile weight, although the x39 cartridge fires a lighter weight projectile than the 308win.
It looks like youre saying first that they are the same projectile weight and then saying that the x39 fires a lighter weight projectile in the same sentance. Am I missing something?
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>>28646559
Yes, although that's why I referred to 7.62 specifically, and not just 30 cal. 303 Brit/.311 dia is 7.7mm
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>>28646578
Yeah, I was just saying because x39 also uses a .311 bullet.
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>>28646571
I meant to say they are the same projectile diameter, not weight*

My bad. For example, I load up 123gr 7.62 projectiles in my 303 (despite the 303 being a 7.7mm/.311" bore, they shoot alright) with trailboss powder for a reduced load.

Then for full power loads I use a 174gr .311" projectile with 40 grains of AR2208
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>>28646602
What 123gr projectiles are you using? Is it for 7.62x39? Because x39 is a .311/.312 diameter round.
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>>28646602
Thanks, thought you had meant that instead but wasn't sure. Whats the difference in weight from? Different projectile composition or maybe different length or slightly different shape but with the same diameter? Im guessing that the diameter is measured at the thickest part.
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>>28646728
Different weight is mostly due to the length of the projectiles.

On the left is a 7.62x39 123gr projectile and the right is the .311" "303 cal" 174gr projectile, both loaded into a 303 British case.
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>>28645446
Custom rounds are usually called "wildcat loads", and when a new cartridge gets standardized, it's usually because a particular wildcat load became popular.

".300 AAC Blackout" is probably the most recent example -- it started out as a wildcat loading, .300 Whisper, then was submitted to SAAMI by AAC to be ratified as an open standard.
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Well, it's time to for me to head to work. Thank you everyone for the education, I learned a lot today. Hopefully this thread is still up by the time I get a break.
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>>28643556
this is a grate illustration of why most people shouldnt own guns.
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>>28643556

case length.

it is a 7.62 mm diameter round in a 39mm case.
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>>28643969

the actual projectile would
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>>28643575
kek
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How come no one pointed out that 9mm is .355"?
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>>28648454
>grate
Think you should own a dictionary before you start proclaiming who should own what.
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>>28648587
Why would I want to wear my barrel with cleaning?
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>>28645424
The benefits of short fat case vs long thin case are:

Shorter length of action, and so shorter lighter firearm. You need your bolt to go backwards for a length of a cartridge + some more to eject spent case and chamber new round. Short cartridge = short bolt travel, short bolt and firing pin, short receiver. Magazine would be smaller along this axis too. Sometimes you want your new more powerful round to fit into existing action or even magazine (6.5 Grendel for example), so with length limited you go for fatter case.

Besides, internal ballistics for shorter fatter cases (rate of powder burn) is more stable. It's not necessary burns faster 'because of being closer to the primer' (burning faster isn't always good, it could generate excess pressures) - you should always pick a powder with just correct burn rate for a given load. But it's thought that in short fat cases burn rate is more consistent between rounds, giving stable muzzle velocity.
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>>28648587
yes YOU do.
>>>/trash/
Thread replies: 63
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