What happened to caseless ammunition?

alfsauve said:

Along the line of fragile. I remember reading about guidance systems for artillery rounds. They had to design electronics that would stand up to several hundred Gs... longitudinally. R&D got them working well in the lab, but every time the military took a case our for a field test they would fail. Seems like the least stress on the other two axis caused internal components/connections to break.

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"We built what they said, but not what they want." I think every tech guy identifies.

Kendal Black said:

"We built what they said, but not what they want." I think every tech guy identifies.

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That exactly. Even as a layman engineer and machinist, I've run into the "what you asked for isn't what you want" problem more than a few times.

If it were me--again, as a student but not professional engineer, and talented but not career machinist--my first thought on the chamber issue would be a field-replaceable chamber, probably fastened onto a barrel extension, tapered at least at the entrance, to house a nose on the bolt including a metal O ring of the design you'd find on a hydraulic shaft. The type that flares under pressure, so any leakage would press it against the walls.
With either a sealed firing pin channel or implementing the seal from a separate primer or base cap on the whole round assembly, I'm 100% certain it would work. Just not for how long.

Deus Machina said:

That exactly. Even as a layman engineer and machinist, I've run into the "what you asked for isn't what you want" problem more than a few times.

If it were me--again, as a student but not professional engineer, and talented but not career machinist--my first thought on the chamber issue would be a field-replaceable chamber, probably fastened onto a barrel extension, tapered at least at the entrance, to house a nose on the bolt including a metal O ring of the design you'd find on a hydraulic shaft. The type that flares under pressure, so any leakage would press it against the walls.
With either a sealed firing pin channel or implementing the seal from a separate primer or base cap on the whole round assembly, I'm 100% certain it would work. Just not for how long.

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So that way we get rid of initial (throat and early rifling) bore erosion too? You throw away the worst of the throat erosion at the same time you fix the gas system.

I like it, but the machine gun boys are going to hate it and curse like Greek tragedy. All the heat of a barrel at swap time, in a part you could hold in your hand if you never wanted to use that hand again.

RedlegRick said:

I personally think cased ammo has reached its pinnacle of development, as has firearm design. Look at the history of edged and melee weapons, where aside from materials and shapes, they remained pretty much the same for millennia. Moving forward in time, the venerable Brown Bess musket was in service for close to three centuries. Other than for special applications, I feel caseless ammo is a dead end myself.

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Uh, no blades did not stay the same for millennia. From copper to bronze to iron to steel. Swords changed greatly. To a large extent the material forced the design. The reason you did not see rapiers earlier than you did was no one could make a blade that thin that long and remain strong and flexible. And to a very large extent armor drove design of swords a great deal. No one wearing steel mail would be worried much about a bronze sword. Swords were constantly evolving and changing. By the 19th century the British alone had engineer, heavy cavalry, light cavalry and Infantry swords and they would change the design of each several times over the century. They really changed their swords more often than their guns.

For those confused by why I am arguing on both sides of an issue: We are talking about a machine that does not exist in any satisfactory form. Please keep going.

Kendal Black said:

So that way we get rid of initial (throat and early rifling) bore erosion too? You throw away the worst of the throat erosion at the same time you fix the gas system..

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Precisely. Of course that's at least two more parts to change, but there's no getting around that without future engineering and refinement.
But it would be a way to fix the issue of chamber, bolt, and possibly even the freebore section after erosion. Just make sure to keep alignment clearances to spec. Design it right, and you could swap barrels just like the crew-served weapons do now.
The problem is that it's not difficult to fix the seal or the gas system or the erosion issues, but it's an enormous pain to fix any combination of them in an autoloading system you expect to handle a few thousand rounds before repair.
Not to mention the issues with caseless ammunition in its own right, but I was studying mechanical engineering, not chemistry.

Let us keep this discussion going. I remind you (y'all plural) that the guys who threw away the book before now were Colt, Mauser, Browning, Stoner and Kalishnikov.

Afterthought edit: Garand too, though his best ideas got overruled.

I feel like I should sketch this out--I just tended to do that, as a garage machinist. Now I'm actually running an idea in my head that would incorporate the 'bolt nose' and firing pin together, for a better gas seal. This creates a further issue about clearing primer cups, though...
Then maybe check across patents before uploading anything.

Come to think of it, making a semi-cased system would be easy. As would an open-bolt caseless one. The tough part is ejecting the primers on the latter, and preventing cook-offs.
Actually, could even seal the firing pin channel on caseless, but then you end up with either protruding primers or making them intentionally set back...
Hmm.

Deus Machina said:

Of course that's at least two more parts to change, but there's no getting around that without future engineering and refinement.

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A challenge for you. Do it with an assembly of three parts. THEN EXPLAIN WHY YOU COULD NOT DO IT WITH TWO.

Yeah, yeah. I got that plenty from teachers and customers before.
I may be able to keep those parts stationary, or replace existing parts with them. The question is if they've been designed before, and if they have, why they haven't been implemented.
I know I could make them function under the pressures I'm used to (my machining was in paintball and pneumatics, so under 1000psi) but not sure how they'd handle 65k without further research.
Or maybe I'm looking at it the wrong way. If chambers are expected to erode anyway, putting a port there to make a piston system double-acting...
Anyway, it would still be much more efficient materially and logistically to use semi-cased stuff. But I'll check into stuff. Even if I couldn't get it to work from my garage, might have a giggle looking through patents. I do have a couple ideas in mind, of varying possibility.

I was working for a while on a design for caseless-ammo guns that used a bolt with a cupped chamber that enclosed the charge and the base of the bullet. The bullet would be anchored in the charge composition by a tail extension that would be surrounded by a priming material that would be composed primarily by combustible metal fibers.
The charge would be ignited by an electrical charge that passes through the bullet itself from the barrel lining and grounds through the bullet tail to the base wall of the cupped chamber. Gasses vented at the mouth could be vented forward, possibly to delay bolt recoil. My original design included a linear magneto that operated by pump-action on coils embedded in the composite barrel sleeve, with the electrical charge being held by a condenser until it is triggered by a microswitch.
The action could be based on pump, lever, long-recoil semi or full auto, or even motorized.
The device was conceived to be a common tool in a book about a somewhat dystopian future, but I see no reason that it could not be built.

That's how I imagined them in sci-fi, and would be the easiest way to do so.
Currently, I don't see a military using an electrical design, though. The ones I'm thinking through still use a rifle primer, and that's the biggest workaround there--still being able to seal while using a firing pin and ejecting the primer when complete.
Electrical systems would just be so much nicer if they could be adapted. No need for a primer or extractor; jams could be taken care of by opening a dust cover and sticking a finger in.

I think electrical priming is a good idea, for it lends itself to a priming that blows out the front with the rest of the crud when you fire.

Remington used electrical ignition in a cased-ammo rifle (which did not prove popular). Voere used it in a caseless rifle, also not popular. Electric primers are used also in model rocketry. So there are some points of prior art to look at.

Electrical firing "lockwork" can be simple and the trigger pull anything you wish, since all you are doing is closing a switch. There is no need for the action to cock the striker or hammer because there isn't one. Going "on safe" consists of flipping another switch. Lock time is infinitesimal.

Kendal Black said:

I think electrical priming is a good idea, for it lends itself to a priming that blows out the front with the rest of the crud when you fire.

Remington used electrical ignition in a cased-ammo rifle (which did not prove popular). Voere used it in a caseless rifle, also not popular. Electric primers are used also in model rocketry. So there are some points of prior art to look at.

Electrical firing "lockwork" can be simple and the trigger pull anything you wish, since all you are doing is closing a switch. There is no need for the action to cock the striker or hammer because there isn't one. Going "on safe" consists of flipping another switch. Lock time is infinitesimal.

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Remington's Etronx primer was one of the first forays of electrically primed small arms cartridge in the civilian market but militaries have been using electrically primed cartridges for decades in medium caliber weapon systems. Most of the US militaries 20mm to 50mm systems use electrically primed cartridges. Some of the big bore stuff like the M256 (Abrams main gun) uses electrically primed cartridges. The M256 is a semi caseless cartridge. The body of the case is a combustible material and only the cartridge base and primer tube are ejected from the breach when it fires. Electric priming is a well developed technology just one that has not been accepted into the small arms arena yet.

That "little puff of gas" has a distinct issue very early in the firing cycle.
There's a hole in the bolt face. A rather large one, through which the firing pin operates.
Despite untold manhours of tinkering, putting the primer on the cartridge centerline is still the most reliable ignition geometry.
The motion of the firing pin against the primer--needed to compress against the anvil--also will displace it from the bolt face, so there's a gap. A gap through which funneling 65k psi gas around is probably a bad idea. That it's generally pointed toward the shooter makes it a tad worse.

HK tried using side mounted primers on rectilinear-cast rounds, but, all the reports were that reliability suffered. The engineering elegance of only having to dispose of fired primers was and is inescapable. But, the practical often gets in the way of th eelegant.

The G11 used a teeny short metallic base (like 3-4mm tall) which obturated and indexed the round.

The G11 had a unique mechanism. The "bolt" was rotary. Rounds were fed in from the top, point down. The bolt unit then rotated into battery. The round fired, the bolt then rotated downward, which ejected the spent rim. All of this was in a carrier that was recoiling back into the receiver. This was part of a concept where a burst of rounds were fired at very high rapidity (≈1200-1500rom), to "feel" like just one recoil impulse. The rotary bolt was not much more than a cartridge length in diameter, as was pretty fast in its 180º rotation.

It was a pretty slick system. With the overhead of obsoleting billions of rounds, magazines, and the like.

I do not think we should rule out binary ammunition in the sense of a liquid fuel and a projectile. The first answer is that it is inconvenient to transport liquids. But every successful army in the history of the world has managed to do that somehow. Water.

By the way, you guys with the water buff truck, you are the real heroes. Better than I, Gunga Din!

A primer could also be attached to a thin tail on the bullet. The tail and primer could act as a stabilizer for the bullet as well as something to form the propellant around.
Alternatively, the tail and expended primer could be driven fully or partially into the hollow base of the bullet by the propellant charge.
In either case, nothing would be left in the chamber but propellant residue.

You, sir, have just restarted my thought process there.
Wouldn't even need a tail or a way to press the primer in post-firing--just leave a pocket on the back of the bullet and press the primer into that.
It would need a few small holes in the jacket or slots at the edge of the primer itself, but that wouldn't be difficult.

Kendal Black said:

"We built what they said, but not what they want." I think every tech guy identifies.

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This calls for the fine art of giving 'em what they need in the guise of what they want.

Merle1 said:

high powered air rifles are not that easily silenced...

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Also, pre-charged pneumatic rifles operate at pressures ranging from 2000 to 4500 psi. Rather puny compared to what powder can generate.

Deus Machina said:

You, sir, have just restarted my thought process there.
Wouldn't even need a tail or a way to press the primer in post-firing--just leave a pocket on the back of the bullet and press the primer into that.
It would need a few small holes in the jacket or slots at the edge of the primer itself, but that wouldn't be difficult.

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The early "Volcanic" rounds used a similar idea, containing both primer and propellant within the hollow skirt of the projectile.

Another variation was the "Needle" gun popular in Europe from around 1860 to 1900 wherein the cartridge case was consumable paper containing a primer "pill" at the base of the cartridge. The firing pin was a long "needle" which would go all the way through the cartridge to hit the primer.

There are no laws that say the priming charge of the future needs to be on the axial center of the round. For a very long time, the whole muzzleloader era, it wasn't, but instead off to one side.

-Or the primer could be at the base of the bullet, like the Chassepot needle gun or non-axial like the pinfires and have the primer compound attached to the bullet's skirt.(although that may lead to feed problems depending on the mode of ignition),

My first thought, for (mental) ease of conversion and to reuse currently available materials: simply leave a channel in the base of the bullet, press in a small rifle primer. Small holes to allow the primer charge through to the propellent.
Little lost weight (unlike the volcanic bullets), nothing left in the chamber. Assuming no misfires, of course.