So why brass as ammunition casing?

[Carbon]

Anyone can tell me why brass is the de-facto metal used in ammunition casing?

Or is it even brass? Is it some kind of brass alloy mix?

I can only assume because it is cheap, soft enough to crimp but, strong enough to keep shape. I would assume to the low friction co-efficient of brass has a small factor in its application.

[Army]

Yes, they are mostly brass, around 96% plus alloys for ductile strength. Some countries have used soft steel as a viable substitute (mostly the former Soviet Union and China).

Cartridge cases don't need to be especially strong by themselves, but must have a certain ductile properties that allows them to expand, then return to its original shape, all in a fraction of a second.

When the powder begins to burn inside a case, tremendous pressures are created. The Remington .223 [NATO 5.56mm] for example, will make close to 53,000 PSI. Yes, 26 TONS of pressure. The .50BMG round will go to nearly 130,000PSI. M1-A1 Tank main gun ammo will exceed 420,000PSI at peak burn.

Anyway, this pressure will expand the case against the chamber walls, not only sealing off the chamber from gasses trying to escape rearward, but forming a momentary bond with the steel of the chamber wall. This bonding will easily handle the pressures involved, which is why the case doesn't have to be strong by itself. Although there is a small amount of rearward stretching of the case (this is because the base, or "web" of the case is much more thick and expands at a slower rate), the bolt face will stop any brass from squirting out the back. Semi and full auto weapons do not unlock the bolt from the receiver until this pressure has dropped to a safe level.

Of course, all things have a limit. Too much pressure, and the case expands too fast to stretch adequately, resulting in splits and cracks, and occasionally total failure of the case (think of Silly Putty, pull it apart slowly and it stretches like gum, but pull it fast and it snaps in two). Rifle bolts are designed to vent away hot high pressure gasses from a case failure so it doesn't hit you squarely in the face. A "blow-up" is a rifle that could not contain the pressures created, and ruptures at the chamber and/or receiver. Rare, but this does occur more times than you would think. Blow-ups occur more frequently in handguns due to ammunition mix ups more often than too high pressures.

Brass is cheap to use, easy to manufacture with, will form any cartridge shape you can imagine, and, most importantly, is non-conductive/non sparking by itself. One last tiny factor, is brass accepts nickle plating very well, which makes for some purty lookin' ca'triges

[WickeDKlowN]

Wow...That was one of the most informative posts I've read in a long time.

[fire1811]

Yes, they are mostly brass, around 96% plus alloys for ductile strength. Some countries have used soft steel as a viable substitute (mostly the former Soviet Union and China).

Cartridge cases don't need to be especially strong by themselves, but must have a certain ductile properties that allows them to expand, then return to its original shape, all in a fraction of a second.

When the powder begins to burn inside a case, tremendous pressures are created. The Remington .223 [NATO 5.56mm] for example, will make close to 53,000 PSI. Yes, 26 TONS of pressure. The .50BMG round will go to nearly 130,000PSI. M1-A1 Tank main gun ammo will exceed 420,000PSI at peak burn.

Anyway, this pressure will expand the case against the chamber walls, not only sealing off the chamber from gasses trying to escape rearward, but forming a momentary bond with the steel of the chamber wall. This bonding will easily handle the pressures involved, which is why the case doesn't have to be strong by itself. Although there is a small amount of rearward stretching of the case (this is because the base, or "web" of the case is much more thick and expands at a slower rate), the bolt face will stop any brass from squirting out the back. Semi and full auto weapons do not unlock the bolt from the receiver until this pressure has dropped to a safe level.

Of course, all things have a limit. Too much pressure, and the case expands too fast to stretch adequately, resulting in splits and cracks, and occasionally total failure of the case (think of Silly Putty, pull it apart slowly and it stretches like gum, but pull it fast and it snaps in two). Rifle bolts are designed to vent away hot high pressure gasses from a case failure so it doesn't hit you squarely in the face. A "blow-up" is a rifle that could not contain the pressures created, and ruptures at the chamber and/or receiver. Rare, but this does occur more times than you would think. Blow-ups occur more frequently in handguns due to ammunition mix ups more often than too high pressures.

Brass is cheap to use, easy to manufacture with, will form any cartridge shape you can imagine, and, most importantly, is non-conductive/non sparking by itself. One last tiny factor, is brass accepts nickle plating very well, which makes for some purty lookin' ca'triges

well this is the book answer
the real answer is because its shiny

[Warewolf50]

well this is the book answer
the real answer is because its shiny

Ohh now i get it, army post didnt help at all.

[fire1811]

exactly

[Carbon]

WOW! thanx Army!

[trains are bad]

I can vouch for that info being 100% correct, too fwiw.

There are plastic cased centerfire ammo, but than is not reloadable, and at high rof ppl have gotten it to melt and deform in the chamber. It's lighter though. I don't think it's waterproof either. An advantage of metal shell casings is how much heat they remove from the firearm.

Shotgun shells are mostly plastic.

[Jonneh]

Check out the H&K G11, a joint project to build a reliable caseless round shooting assault rifle, while it's not very viable (mainly because nobody makes ammo for it, and the bolt mechanism is hilariously complicated), it's very cool. The idea to use caseless rounds means that users don't have the weight of all that brass with them. so a current M16 wielding soldier (who carries 5 * 20 round magazines If I recall correctly) can, with the same mass, carry around 10 * 50 round mags.

New things make me salivate.

[Head knight of Ni]

Yes its the age of the super guns. There are working rigs that can fire up to 1,000,000 rpm. These things look like a big box and fire caseless ammo electronicly.

[SlartyBartFast]

Check out the H&K G11

Here's a good page. http://www.shadowsource.org/dragon/g11.html

2100 rpm

[Phelps]

Ditto everything Army said, with the caveat that there are other materials out there. Wolf Ammunition (out of Russia) as an example uses milled steel for their casings. (I almost said "their brass." Heh.) The main thing, IIRC, that brass has going for it is that it is easy to mold in manufacturing, rather than a harder material like steel, which has to be milled.