How Does Caseless Ammunition Work?

As an Amazon Associate I earn from qualifying purchases.
Our Associate portal can be found here

When you hear the word Caseless it refers to complete ammunition, that upon firing, it will not leave behind a part of itself. It begs the question, how does caseless ammunition work? Generally, caseless ammo works the same way as regular ammunition. The difference is the chamber of the gun will seal more tightly, and the case is absent from the round.

Researchers and hun developers have for many years been trying to perfect caseless ammunition to modern acceptance. The advantages would be immense especially if you consider common issues of weight and expense from brass cases. Soldiers in combat would easily carry more ammo and it would cost less to produce more ammo.

However, the problems are many. In some cases, when the prototype caseless ammo was tested with Smith and Wesson, many years ago the entire magazine of ammunition tended to ignite. It is harder to seal the breech of a firearm that uses a cartridge without a case. The typical brass case performs so well in this aspect. Ignition for caseless ammunition is electrical since it prevents the bits of a conventional primer from floating around in the action of your firearm after the propellant burns away.

There is always the risk that the power residues may foul the electrical connection. 

The caseless designs are not as sturdy as the standard brass cartridge case. The bullet must attach to the solid propellant using an adhesive. The more durable the caseless cartridge is the harder it is to ignite.

There have been some advances in making caseless ammo military prototypes for use in cannon-sized rounds and it has shown some glimpse of promise. But I can say with some level of certainty that we will not see caseless ammo for small arms in the immediate future.

What are the Benefits of Caseless Ammo?

The primary benefit to all caseless ammunition comes from its name. The lack of a cartridge case. Consider the following benefits.

Lighter Ammunition

Caseless ammo boasts big reductions in weight. When you get rid of the weight from the metal cartridge case you potentially reduce the volume of the ammunition. For the same reason that you do not need a case component, you end up saving on precious material.

Consider the example of a 5.56x45mm cartridge:

Each complete cartridge consists of the cartridge case, bullet, powder, and primer.

For a 55 grain bullet, it is loaded with 25 grains of powder and the case and primer weigh 96 grains. In theory, getting rid of the case will save you 90 grains of weight from each cartridge. It sheds off roughly half the weight from each cartridge. 

However, it is not the way caseless ammo works since caseless ammunition will not work well by just stacking a primer with loose powder and a bullet. In essence, the resultant cartridge will most likely save about ¼ of the total weight of a traditional cartridge.

Physical Packaging of the Ammunition.

By removing the cartridge case from the system, you also remove the potential source of causing a jam in your firearm. If you consider the traditional way of using a powder behind the bullet, it makes it easy for the bullet to be broken off from the propellant. Therefore, instead, of using a bullet into the propellant, the bullet is almost encapsulated within the propellant. It also leads to maintaining a unified cartridge.

Provide a Higher Cyclic Rate of Firing,

You do not need a combustible adhesive or a propellant that can be formed to shape. It is because there is no need for the firearm to perform an extraction of the spent case after every shot. A higher cyclic rate needs a larger capacity magazine, on a more compact weapon. 

Easy and Faster Reloads

If the firearms community was to popularize the use of caseless ammo again, magazines would probably be different. The ammo would probably be issued in pre-loaded, tubes or disposable boxes that would slot into the weapon. It would make it potentially simpler as you will not need a complex mechanism to eject the empty case. There will also be no need to use lots of energy to open the breech and reload it.

Problems Associated the Use of Caseless Ammunition 

There are lots of potential issues that may arise. It may range from finding a propellant that is moisture-resistant, consistent, reliable, and heat resistant, to a weapon that can chamber ammo different from the common ones.

The Durability of the Propellant. 

When using cased ammunition, it is impervious to environmental conditions. It is tough and will resist damage as it can take a lot of heat that may cause the powder inside to spontaneously combust. The same is not true for caseless ammo. When using traditional ammo, the metal case is an ejected heat sink.

Caseless Ammo is a clockwork nightmare on the inside

Making a weapon that uses caseless ammunition is a hurdle. An example of a firearm that fires caseless ammunition is the HK G11. It remains the only firearm that was the closest to get an approval into service. The HK G11 looks simple from the outside, as it is just a big brick of a rifle. However, it is well sealed, and this prevents dirt from getting inside. 

I am sure there are some groundbreaking ways to develop the HK G11 to a simpler mechanism. But I doubt if there will ever be a simpler way to use a firearm than it is for the cased ammo. The only complication when using cased ammo is the ejection system is somewhat complicated. But the mechanism is as simple as a flat spring on the side of the bolt that will grip the rim of the cartridge to extract the case from the chamber. Also, the use of a simple blade of metal as part of the receiver kicks the case off of the bolt face, as the bolt travels back in the receiver.

Our understanding of firearms is progressive over the years to the point where we can develop a reliable rifle that can fire thousands of rounds without a single jam.

A caseless firearm does not have a way to eject, or clear the chamber of a live round. It can be a potential danger when you have a failed primer, or when you need to make the firearm safe for transport, disassembly, and cleaning.

Is a Caseless Ammunition Feasible

In theory, caseless ammunition is operational and superior to cased ammo. However, the difficulty is the fact that all firearms are a tightly integrated weapon system. The many attempts to popularize caseless ammunition are just the same as those of replacing steel cars with aluminum. It can work, but a single change in design and function affects everything about the system. The details require a redesign from the whiteboard up. 

Sub-standard Copy Cuts

The first reason why caseless ammunition is not modern-day ammunition is that there are not so many standard caseless versions that have been commercially released. Also, the production of caseless ammo makes for a material challenge. It is near impossible to come up with an explosive that is stable under every conceivable situation. 

Bullets get dropped, abraded, shocked, crushed, burned, soaked, shot, overheated, and aged among other harsh treatments. It took hundreds of years for modern bullets to get to the point they are today and that is why they go off only as they are supposed to.

Poor Design

The second reason caseless ammunition is not a favorite is that the ammunition is in the gun. There are a lot of things that must happen in the correct sequence. A mechanical system moves the ammo around and we know that metal-on-metal is more forgiving than metal-on-caseless. 

Afterward, the explosion must happen in a controlled setting, with a sealed chamber as the explosion propagates. When using a telescoped caseless ammunition, the overall bullet is shorter because the round is surrounded by a propellant. The explosion must first start by pushing the bullet forward before the rest of the explosion finishes.

The explosion needs to be clean because any residue will foul up the mechanical parts. If this happens, it can make the stuff used to make the caseless material strong not to burn correctly in the brief explosion.

When using cased ammo it would normally seal against the various chamber parts making it a disposable, controlled environment for the explosion. Caseless ammo in the chamber is under direct exposure to every explosion. And when the traditional case is ejected it takes lots of heat and soot along with it. The caseless ammo leaves all the heat and soot inside the mechanism.

Unreasonable Requirements

A third major reason why caseless ammo is not feasible is that to make it work, you also have to make an entirely new gun that works too. There is also the added difficulty of the fact that cased ammunition already exists. Caseless ammunition should be an improvement and as things are, it is not a necessary improvement.

For military use, the requirements of ammunition are tough. All ammo must be able to handle rough and extreme levels of both heat and cold. It is an advantage if you can store the ammunition indefinitely and not explode when ignited. 

The weapons must portray some demonstrable improvement over conventional designs. For example, a high cyclic rate is what the caseless ammo promises but modern thinking prefers the use of three-round bursts as opposed to a rapid burst of continuous fire. It is hard to see a high capacity magazine as an advantage.

Making a caseless cartridge that will reliably feed on a belt is also a potential challenge. There is no need to have the logistics of two kinds of ammunition when one can suffice, as you risk igniting the entire belt up in flames should one round be hit accidentally.

For every upside, there is a downside, and as it stands the downsides seem to be more than the upsides.

Most Popular Ammunition Accessories


Caseless ammunition has been tried and found wanting. Even though the ammunition design is typically the holy grail of ammo, it is an engineer’s worst nightmare. If the idea comes to fruition, it may obsolete the cartridge case overnight as it means having a cheaper, lighter, and more compact ammunition. 

The firearm would be able to carry more than 50 rounds in slim, and inexpensive magazines that can expel them at a higher rate. The result is having a complete firearm that does not need lots of maintenance during combat. 

Unfortunately, caseless ammunition has some problems with breech obturation. The deposits of burnt powder or propellant that the gun ejects, will still be left inside the breech. Until there is some sort of breakthrough that makes the propellant eject safely, then the entire notion of having caseless ammo sooner is a nonstarter. 

Amazon and the Amazon logo are trademarks of, Inc, or its affiliates.

Scroll to Top