Will caseless ammo ever become popular?

[Yugopap4me 29]

Caseless ammo has been around for a long time. And has been used in everything from the simple daisy VL 22 to the complex G11 and the futuristic metalstorm firearms. But why has none of this ever gained popularity? With the cost of ammo and metals always going up why wouldn't companies invest in finally working out the bugs in caseless technology?

[breid1970 327]

Probably cost effectiveness. But I could be wrong.

[XD45 7,124]

From the Wikipedia entry on Caseless Ammunition

 

Heat sensitivity

The first major problem, of special concern in military applications, which often involve sustained firing, is the heat sensitivity of the ammunition. Nitrocellulose, the primary component of modern gunpowder, ignites at a relatively low temperature of around 170 °C (338 °F). One of the functions of the metallic cartridge case is as a heat sink; when extracted after firing, every metallic case carries away a significant amount of the heat from the combustion of the propellant, slowing the rate at which heat builds up in the chamber. The thermal insulation provided by the case also works the other way around, shielding the propellant from built-up heat in the chamber walls.

Without a case to provide these functions, caseless rounds using nitrocellulose will begin to cook off, firing from the residual chamber heat, much sooner than cased cartridges do.

The normal solution to the problem of heat is to increase the heat resistance by switching to a propellant with a higher ignition temperature, typically a non-crystalline explosive carefully formulated to provide an appropriate rate of combustion.^[1][6]Heckler & Koch, in concert with Dynamit Nobel, managed such a task by producing relatively heat-resistant caseless ammunition.

Sealing

Another important function provided by the cartridge is to seal the rear of the chamber. During firing of a cased cartridge, the pressure in the chamber expands the brass and blocks the chamber. This prevents gas exiting from the rear of the chamber, and it has also been experimentally shown to provide a significant amount of support to the bolt. Without the case to provide this seal, the firearm design must account for this and provide a means of sealing the rear of the chamber. This problem was also encountered with the Dreyse needle gun; the French Chassepot solved the leaking-breech problem with the addition of a rubber seal to the bolt.^[8][9]

Telescoping caseless rounds must also deal with the issue of blocking the bore, as the bullet is surrounded by propellant. The booster charge is used to address this issue, providing an initial burst of pressure to force the bullet out of the cartridge body and into the barrel before the body combusts.^[7]

 

Fragility

Caseless rounds are limited by the fact that the cartridge body is primarily a propellant, and structural properties are secondary to the combustion properties. The primary issue is one of extraction. While caseless ammunition eliminates the need to extract a fired case, unfired cases must be extracted in case of a misfire, or to unload the firearm. In metallic cases, this ability is provided by a rim or extractor groove machined into the rear of the case. Even in completely plastic bodied cartridges, such as the Activ brand shotgun shells, a thin metal ring is molded into the rim to provide support for the extractor.^[4][6][7]

Edited September 15, 2013 by Darth Saigus

[siminov 164]

I'll have to search but I remember reading about a guy who was using the casings as the projectile. Can't remember how effective it was but it was pretty cool.

[uzitiger 193]

Don't forget barrel heat.  I heard from a Yom Kippur and Six Day War veteran telling me how he fired the Browning .30 cal machine gun until the barrel was glowing red hot and he could see the bullets going down the barrel.  Caseless ammunition would have a danger of cookoff.  It would take a lot of development to get caseless ammunition to work.  I have seen plastic cased 5.56 ammo sold at a show a number of years ago.

[XD45 7,124]

From the Wikipedia entry on Caseless Ammunition

 

Heat sensitivity

The first major problem, of special concern in military applications, which often involve sustained firing, is the heat sensitivity of the ammunition. 

 

 

Don't forget barrel heat. 

[belt fed frog 56]

uzitiger,

 That was NATEC (mfg.)  ammo it flopped  the military found it wanting in several aspects many related to the same problems as caseless .

 

It is now known as PCA (polymer cased ammo ) and is starting to be re marketed as Civi  ammo .

 

Caseless has been around for more than 50 years and always cost more than brass cased  in single shot applications it does work  but no one has made it work well in F/A`s,  they even tried a nitro plastic self consuming case  in  20 mm rotary guns and it failed miserably .

Only has Nitro plastic cases worked well in tank shells and they still have a metal case head to eject .

 

The current ideal is liquid propellant no case and they have been playing with it for 15 years it works in tests  but that is as far as they have gotten with it .

 

You may see PCA on the consumer market in years to come both reloadable and non reloadable (more likely) but not in Military applications . 

 

We had a guy with some NATEC  50 BMG cases shoot a match some years ago and it shot fairly well  ,he reloaded it at the bench and seated the slugs by hand and it did not shoot as well on second firing because neck tension is important to accuracy . .