Handgun/rifle: what if propellant is replaced with high explosive?

Factual Questions
1

AIUI, a firearm cartridge contains a shock-sensitive high-explosive primer that detonates and ignites the main propellant charge, with the latter then deflagrating at a fast (but subsonic) reaction rate.

What happens if the main propellant charge is replaced with an equal mass of high explosive that undergoes true detonation when the trigger is pulled? Are the parts of any given handgun or rifle strong enough to contain the higher pressures that would result? would the bullet be deformed by the extra high pressures behind it? Would the portions of the brass cartridge that are not braced by the barrel or bolt/slide be expected to rupture?

ETA: reported for move to GQ

2

Thread relocated from IMHO to GQ.

3

Well you have realised that the pressure must be well above the proper pressure.
The impact from the explosion will be well above the force of the maximum force the chamber and other parts can handle.

Besides, Modern guns are not able to handle pressures high above their rated pressure.

going above maximums leads to premature wear, and cracking, and cracking leads to explosive failure which means injuries.
Why ? Not only could the chamber or barrel simply fail and explode apart… but the bullet itself is being hit with a higher force and it could deform and therefore jam in the barrel …
The gun powder is designed to burn slow enough that its burning while the bullet travels along the barrel. Its basically for the same reason that gasoline/petrol has it that slower burning is better !

4

The gun would exhibit properties closer to a hand grenade than a firearm.

5

How much HE does a hand grenade contain?

As I think about it, I recall a video demonstration of proper HE use for demolition. the technician had several concrete columns (each maybe a foot in diameter) at a test site, and showed the effects of various configurations of a set quantity of HE:

-HE charge fixed to the side of an intact column; the result was hardly any damage.

-HE charge placed in hole drilled to center of column; this did more damage, but much of the blast energy escaped out of the drilled hole.

-HE charge placed in hole drilled to center of column, with sand packed into the hole all the way from the charge to the surface of the column. The mass of the sand, even though it wasn’t cemented together, worked to confine the blast energy, forcing it to shatter the concrete around it instead of fleeing out of the drilled hole; the result was that the concrete column was pretty much obliterated.

So I suppose something similar might be expected for a gun with a HE propellant charge. The bullet is free to move, but it can’t get out of the way fast enough to relieve pressure in any meaningful time frame. I guess my question was whether the various parts of the gun (being steel rather than concrete) would be expected to fail after many such firings, or would they be expected to come apart on the very first event.

6

If I may, I’d like to piggyback a secondary question on this one - rather than using an equal mass of high explosive to the powder charge, is it technically possible to use a smaller mass of high explosive and still achieve the same propellant effect as the original black powder charge, or is the pressure gradient (or some other factor) still likely to be a problem?

7

the problem with a high explosive isn’t necessarily the peak pressure, but in the way that pressure is delivered. explosives detonate i. e. burn “instantly” all at once and generate a supersonic shock wave. it’s the shock which damages things; the same phenomenon is how pre-ignition/detonation in a gas piston engine will crack pistons.

And when you get down to it, a gun is basically a piston engine; you want the fuel/propellant to deflagrate (burn smoothly) and deliver as much pressure as possible while the bullet/piston is in the barrel.

8

6.5 oz of Comp B.

9

Allegedly.
Filling cartridges with high explosive is a good sabotage method.
Your enemy picks up and uses them, Kaboom!
one injured or dead comrade.

10

Anecdote time. A friend of mine would load his own cartridges. He tended to load them hot. He would load each round with the upper recommended amount of grains or beyond. One day at the range his Smith and Wesson .44 magnum blew up in his hand. The cylinder of the revolver cracked in two. The weapon could not handle the added pressure of a little more low explosive. Using high explosive would be catastrophic.

11

Sure, but you only have the length of the barrel to apply accelerating force to the projectile, so increasing the exit velocity becomes something of a game of diminishing returns - so there are perhaps potential drivers for wanting to increment the pressure more rapidly.

12

Interesting idea. If you could convince the enemy that their ammunition supply is tainted it could lead to all sorts of chaos.

13

afaik this is actually done for some calibers which are widely used for both handguns and long guns. e.g. a handgun .44 Magnum cartridge would be loaded with a faster-burning powder, while for a .44 Magnum rifle you’d want a slower-burning powder.

but honestly, if you don’t have a huge muzzle flash you’re likely not “wasting” too much of the powder’s energy.

14

Modern propellant powders come in varying grain sizes, densities, and burn rates for different purposes. Reloaders experiment with all this stuff working from tables published by the various powder manufacturers.

In many cases there’s room in the case for a lot more powder than you should use. Which results in excessively hot loads a la Loach’s friend.

Once in awhile you find a legit combo where the case is so large & the powder so dense that you can physically fit two charges into the case. Woe betide the reloader who loses track of what he’s doing and double charges a case. That’s close to 100% guaranteed to destroy the gun its fired in, perhaps maiming or killing the shooter.

More typically the proper load of powder mostly fills the case, so an inadvertent double charge would be obvious as most of it spills out onto your bench.

Interestingly, comparing this Composition B - Wikipedia and this Smokeless powder - Wikipedia we see the detonation rate of the ingredients is not that different. Which partly disagrees with what some folks upthread have said.

A key difference is the Comp B HE is cast as a solid block, not as a loose powder. Smokeless powder also includes various chemical retarders and carefully controlled grain size and shape to manage the rate of conversion from solid to hot gas. So even though the separate ingredients of smokeless powder *can *detonate, a properly finished cartridge doesn’t.

15

Something similar occured in India while it was under control of the British East India Company, leading to the Indian Rebellion of 1857 (Sepoy Rebellion).

*The final spark was provided by the ammunition for the new Enfield P-53 rifle. These rifles, which fired Minié balls, had a tighter fit than the earlier muskets, and used paper cartridges that came pre-greased. To load the rifle, sepoys had to bite the cartridge open to release the powder. The grease used on these cartridges was rumoured to include tallow derived from beef, which would be offensive to Hindus, and pork, which would be offensive to Muslims. At least one Company official pointed out the difficulties this may cause:
unless it be proven that the grease employed in these cartridges is not of a nature to offend or interfere with the prejudices of caste, it will be expedient not to issue them for test to Native corps.
However, in August 1856, greased cartridge production was initiated at Fort William, Calcutta, following a British design. The grease used included tallow supplied by the Indian firm of Gangadarh Banerji & Co… By January, rumours were abroad that the Enfield cartridges were greased with animal fat.

…At Meerut, a large military cantonment, 2,357 Indian sepoys and 2,038 British soldiers were stationed along with 12 British-manned guns. The station held one of the largest concentrations of British troops in India and this was later to be cited as evidence that the original rising was a spontaneous outbreak rather than a pre-planned plot.[61]

Although the state of unrest within the Bengal Army was well known, on 24 April Lieutenant Colonel George Carmichael-Smyth, the unsympathetic commanding officer of the 3rd Bengal Light Cavalry, ordered 90 of his men to parade and perform firing drills with the new cartridges. All except five of the men on parade refused to accept their cartridges. On 9 May, the remaining 85 men were court martialled, and most were sentenced to 10 years’ imprisonment with hard labour. Eleven comparatively young soldiers were given five years’ imprisonment. The entire garrison was paraded and watched as the condemned men were stripped of their uniforms and placed in shackles.*

16

Have a look at Project Eldest Son.

Basically, it was an operation during the Vietnam War, where U.S. special forces would place altered ammunition, both small arms and artillery shells, within VC/NVA/Pathet Lao ammunition caches and upon dead enemy. Placing one booby-trapped cartridge within a full magazine on the dead enemy, was a common means of dispersing the ammo. When the enemy tried to use the ammunition later…well, the article describes it like this:

Later information warfare strategies were then used, like placing on dead Communists, forged reports from Communist higher authorities that the ammunition was safe, and that rumors otherwise would be severely punished; running Armed Forces Radio and TV broadcasts warning US servicemen of the dangers of using captured Communist small arms due to their poor metallurgy; faked US intelligence reports about bad quality control within Warsaw Pact ammunition supply factories, etc…

Worked until the press got a hold of it, and spoiled everyone’s fun.

17

The wiki for “Bulk loaded liquid propellants” details attempts to use liquid solutions as rapidly loadable artillery propellant. Often, low explosives such as propylene glycol dinitrate, were used to comprise the solution. Results were poor, with, from the wiki:

I’m kinda curious what info posters like smithsb, Tripler, or anyone else who’s worked extensively with ordnance or EOD, can add.

18

Slow burning propellant and fast burning propellant are relative terms. They both burn within milliseconds of being ignited. The gas pressure expands at a relatively slow rate (zero to 700fps, zero to 4,000fps) until the projectile exits the barrel, at which point the gas (and unburned powder) will pass the bullet at over 5,000fps.

All rifle, pistol, revolver, shotgun manufacturers, custom barrel and action makers, and propellant manufacturers build their products to the Sporting Arms and Ammunition Manufacturers Institute (SAAMI) standards.

It’s assumed that cartridge built to SAAMI standards will fire safely in a rifle built to SAAMI standards.

My first thought at someone’s replacing modern smokeless propellant with HE would be to call my brother. He’s never seen a firearm explode. :slight_smile: But on a more serious note, if a small amount, certainly not one of equal mass, of HE were to be substituted for the usual brand, shape, and recommended weight of Wonderbang xxxx, it would have to closely match the pressure expansion rate, and burn time, of the recommended propellants.

Interior balistics (what happens inside the firearm) covers many steps. First, the primer has to be crushed and ignited. 2nd, the HE has to be ignited in a controlled, repeatable manner. 3rd, the gas pressure has to overcome the crimp holding the bullet. 4th, the gas pressure then has to overcome the swaging effect of the bullet entering the forcing cone. 5th, the pressure has to overcome the friction of the bullet’s bearing surface on the lands and grooves as it travels down the entire length of the barrel. The final step being the bullet poping free of the muzzle. Except for the last step, which decreases the gas pressure, each step impeads the free flow of the bullet, and increases the gas pressure.

If the gas pressure exceeds the design limits of the barrel, or the action, of the firearm before the bullet pops free, you’re gonna shoot your eye out kid.

As an after thought, smokeless propellent is packed loosely, and unburned/soon-to-be-burned-powder is free to travel down the barrel behind the bullet. Isn’t HE a formed explosive? Would that make a difference in the burn rate? Would the gas pressure in the chamber area exceed design limits before the bullet exits the muzzle?

19

Just to nitpick a little - modern firearms don’t use black powder, they use some variety of smokeless powder. Generally the only firearms that you’ll find that use black powder are antiques, replicas of antiques, and ones designed specifically for black powder hunting season.

20

One thing to remember is that although smokeless powder has a controlled burn rate, it is ***very ***fast. The maximum pressure in a revolver cartridge is reached before the bullet makes the jump to the barrel. Derringers perform just fine with the tip of the bullet practically at the end of the barrel. A 9mm derringer may have only 1.25" of travel.

An M16/AR 15 bullet reaches maximum pressure after 1.75" of travel, and that is a slow burning powder. It still accelerates the whole length of the barrel, but the rate of acceleration drops off.

Dennis