Caseless firearms with separate projectiles and propellant?

[cluttonfred]

There have been a number of attempts at caseless ammunition in firearms seeking the weight savings and mechanical simplicity from never having to carry around or eject cartridge cases again.

I wonder, have there been any attempts to separate the propellant from the projectile altogether, so you'd end up with a magazine holding only projectiles and a reservoir (separate or integrated into the magazine) holding powdered, liquid or gaseous propellant?

 

[Avimimus]

Most tranquilliser guns work that way (with the more powerful ones using CO2 tanks rather than compressed air).

It is interesting because it conceivably would allow modifying the amount of propellant for the same bullet. This might make it possible to use the same chamber more easily for sub-sonic (quiet) rounds and high velocity rounds. Although I suspect that such applications would work better for larger caliber weapons.

 

[shaba]

http://www.youtube.com/watch?v=J_hnC6x036Q
i think the loronzoni repeating flintlock fits the bill .
allso chin in one of his books describes a aircraft cannon that worked like the treeby chain gun with the proppelent and the primer loaded into one end of a explosion chamber and the bullet in the other.

 

[cluttonfred]

Neat stuff, but I had in mind something a little bit more modern. ;-)

 

[Tony Williams]

I wonder, have there been any attempts to separate the propellant from the projectile altogether, so you'd end up with a magazine holding only projectiles and a reservoir (separate or integrated into the magazine) holding powdered, liquid or gaseous propellant?

Yes. The US carried out various experiments with liquid propellant systems, in which the projectile was loaded first then the requisite quantity of liquid was squirted from a reservoir into the chamber the instant before firing.

I have read of an aircraft cannon being designed to use this, possibly in the 1970s, but the most recent attempt was a 155mm self-propelled artillery piece in around the 1990s. The big advantage in this application is that the quantity of propellant could be varied very finely, so that the autoloading gun could rapidly fire several rounds at slightly different elevations and velocities, so calculated that all of the shells would arrive on target at the same instant, to devastating effect.

The main problem is the obvious fire/explosion risk should the propellant reservoir be hit by enemy fire. The answer to this was to use two different liquids which would only burn when combined, which only happened the instant before firing. Problem was, that complicated the whole business considerably. In the end the idea was dropped as technically too difficult.

 

[Rickshaw]

Another advantage of liquid propellants is "regenerative" guns - basically they keep pumping propellant into the chamber as the gun fires, so that it effectively it uses more propellant than the chamber could normally effectively contain if it was a solid. This increases muzzle velocity appreciably. The US Army's Crusader SPG system looked seriously at this form of liquid propellant system but as Tony suggests, the technical problems were too great to make it work. Personally, I think liquid propellant small arms might be rather difficult to pull off. Pipes, reserviors, pumps, etc. tend to be difficult to maintain in vehicles, let alone on a soldier's back.

 

[cluttonfred]

At the level of the individual firearm, I imagine the solutions would have to be much simpler than the complexities which could be accepted in an artillery system.

For me, the concept brings to mind some sort of disposable plastic magazine holding the projectiles in the conventional way but including a pressurized liquid or gaseous propellant reservoir and a battery for power. Perhaps if the propellant used had an unusually high ignition temperature it would be safer? For small calibers in particular, the gain in magazine capacity would be dramatic--for example, while the bulllets would have to be more cylindrical in shape to stack nicely, 50 5.7mm projectiles would easily fit in the space occupied by 20 FN 5.7×28mm cartridges-- a PDW no bigger than a Mauser C96?

In any case, the point of this thread is not for me to fantasize--I just can't believe that this hasn't been tried with powdered, liquid or gaseous propellant at the level of a personal firearm.

 

[sferrin]

I doubt the guy on the field would want to deal with the added complexity unless it shaved some serious weight, enabled a significant bump in rounds carried for the same weight, or gave them something like 5000 fps for the same weight. Even then my money would be on them saying "pass".

 

[Rickshaw]

One of the major advantages of cased ammunition is that it comes in convenient packages which protect the propellant from exposure to the elements and from damage while preserving it for years, even decades safely. One of the problems with caseless ammunition is that it loses that protection and has to have it provided by other means (pouches/boxes/etc). Liquid propellants bring their own problems, which I've alluded to - liquids leak, tend to be flammable and require specialised handling procedures and methods of transport in the field and from the reservoir(s) to the weapon. If pressurised they need to maintain that pressure sometimes for years at a time, when in storage. This tends to add complexity and cost. The more the problem is examined, there needs to be a quantum leap in capability to make it's use worthwhile. I can see if being used in artillery but not in small arms.

 

[Ant-ant]

Most tranquilliser guns work that way (with the more powerful ones using CO2 tanks rather than compressed air).

It is interesting because it conceivably would allow modifying the amount of propellant for the same bullet. This might make it possible to use the same chamber more easily for sub-sonic (quiet) rounds and high velocity rounds. Although I suspect that such applications would work better for larger caliber weapons.

Compress air in air guns r up to 4500 psi / 300 bar

 

[Scott Kenny]

Compress air in air guns r up to 4500 psi / 300 bar

But the projectiles themselves are still pretty limited in velocity. Very few air guns can manage to break the speed of sound. The large caliber ones do manage to get up to roughly .45ACP levels or so, however.

 

[riggerrob]

Separate propellant and projectile would allow a very short recover/action.

Start with a tilting (ala. Martini) or revolving breehblock (ala. revolving pistol magazine) and install the propellant magazine ahead of the breechblock.
Install the projectile magazine just aft of the rear face of the barrel/chamber.

A revolver is better suited to high rates of automatic firing. Perhaps even make deep cut-outs in the outside profile of the cylinder. These cut-outs would be deep enough to allow pushing projectiles straight forward into the rear end of the barrel/chamber. …. to allow inserting projectiles (into the barrel chamber) when the cylinder is out of battery.

When the breechblock swings/revolves out of battery, propellant is stuffed rearwards into a hollow in the breechblock.
Meanwhile, a projectile is stuffed forward into a shallow chamber in the aft end of the barrel. The chamber is barely longer than the projectile.

Rotate or swing the breechblock into alignment with the barrel - maybe squeeze it forward to seal a forcing cone - fire and repeat the process.

If you are still using brass propellant cases, then eject the spent cartridge case forward.

 

[riggerrob]

One of the major advantages of cased ammunition is that it comes in convenient packages which protect the propellant from exposure to the elements and from damage while preserving it for years, even decades safely. One of the problems with caseless ammunition is that it loses that protection and has to have it provided by other means (pouches/boxes/etc). Liquid propellants bring their own problems, which I've alluded to - liquids leak, tend to be flammable and require specialised handling procedures and methods of transport in the field and from the reservoir(s) to the weapon. If pressurised they need to maintain that pressure sometimes for years at a time, when in storage. This tends to add complexity and cost. The more the problem is examined, there needs to be a quantum leap in capability to make it's use worthwhile. I can see if being used in artillery but not in small arms.

To prevent contamination, ship ammo in magazines that are pre-loaded and sealed at the factory. Just before loading, the soldier rips off the top seal and shoves the magazine into the magazine well. Once inside the mag well, the rifle will protect ammo against 95 percent of contaminants.

This only becomes cumbersome when a soldier only fires a few rounds during the initial engagement/ambush then carries a half-loaded weapon for the rest of the week.

If you don’t want to use chemical explosives, then CO2 cartridges can be pre-loaded into the same factory-sealed magazines. CO2 cartridges will cheerfully hold pressure for decades until punctured. To learn the finer points of long-term CO2 cartridges, look at emergency flotation.

 

[Ravinoff]

A German firm called Diehl AG has been kicking this idea around since at least the '70s. There's very little info available (that I've been able to find, at least), but what I could dig up is here.