>>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.
>>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?
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.
.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.
>>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.
>>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.
>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.
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?
>>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.
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?
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
>>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.
>>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?
>>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?
>>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.
>>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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