What's the practical limit on handgun muzzle velocity?

[Flechette]

I am wondering how fast we could get a handgun bullet to go. Let's assume that metallurgy is not a problem. Use a barrel with a 12 inch diameter and a battleship breech lock. No matter what the barrel will not burst.

Given this assumption, how fast could we get a bullet to go? Can we triple, quadruple cartridge pressure or does the powder have some limit? As a thought experiment, if the pressure can be 1,000,000,000 psi we can get that bullet pretty darn fast. What engineering limits prevents us from that?

 

[RX-79G]

If you want to assume that physics has taken a vacation, one of the limits you have is recoil. If you get a bullet going 10,000 miles an hour, the 2 pound gun is going to be moving a couple hundred MPH in the other direction.

But metallurgy is a real thing and can't be sidestepped. High enough pressures and temps will consume the bullet and gun before anything starts to move.

 

[Flechette]

If you want to assume that physics has taken a vacation, one of the limits you have is recoil. If you get a bullet going 10,000 miles an hour, the 2 pound gun is going to be moving a couple hundred MPH in the other direction.

But metallurgy is a real thing and can't be sidestepped. High enough pressures and temps will consume the bullet and gun before anything starts to move.

So what if you put a bunch of RDX behind a saboted steel bullet. Could you get say, 8000 fps?

Is there a limit to how fast the combustion gases can expand?

 

[DeepSouth]

I once read in an article the actual explosion of most gunpowders expanded at just under 6,000 fps, so the theory was the max achievable velocity also just under 6,000 fps.

I have no idea if any of that is true, I just remember reading it in a gun magazine sometime.

 

[RX-79G]

So what if you put a bunch of RDX behind a saboted steel bullet. Could you get say, 8000 fps?

Is there a limit to how fast the combustion gases can expand?

I doubt it. The amount of heat necessary to get the pressures needed would just burn the chamber and bullet. It is kind of like building a rocket that has a nuclear detonation inside to power it. The gun can only contain so much energy before that energy will find other ways to expend itself.


I think the best answers to your questions are these articles:
https://en.wikipedia.org/wiki/Muzzle_velocity Lists a velocity max of 5600 fps for kinetic gunpowder cannon (M1 Abrams sabot rounds, probably)
https://en.wikipedia.org/wiki/Light-gas_gun Works like a giant spring piston airgun, which allows the gas pressure to build slower and remain higher for longer with less heat than standard combustion.

 

[stringnut]

The eargesplitten louden boomer, 378 Weatherby necked to 22, got about 4600 feet per second. Ammunition powders do , as mentioned , have a top speed of about 6000 fps. You can never reach that speed because of friction, expansion ratio, loss of energy to heat and other factors. Many explosives have a much faster pressure wave. The problem is that the pressure is of very short duration. If peak pressure is the same with two powders and one has a longer peak pressure the longer peak pressure will develop the higher velocity. You may touch off something that has a 10,000 fps pressure wave. However if it drops to 0 before the bullet exits you may not get more velocity.

 

[CZ9shooter]

I once read an article on rail guns. It talked about there being an upper theoretical limit to the projectile velocity of conventional firearms due to the powder expansion rate topping out at a certain number. I forget what they said, but it was a pretty high number.

Anyhow, back to railguns. The article claimed that they are not hindered by any such limitations. The speed of light is the only physical law that a rail gun must adhere to. Orders of magnitude higher than any powder could hope to achieve. Strength of materials is another story though. A very powerful gun, at current technology levels) would destroy itself. Pretty interesting stuff.

 

[RecoilRob]

Also consider that firing a projectile through the thick soup of our atmosphere puts a severe constraint on the design and materials that can tolerate the heat generated by hyper velocities. Even if you could get 5000fps out of a pistol...what would you need to make the projectile out of to prevent it from destroying itself within 50 yards of the muzzle? Tungsten or DU come to mind...and the darts that tanks fire are designed to survive being launched at their serious velocities.

Handguns by their definition cannot have a long enough barrel to contain and direct the high energy gas expansion to match what the much longer barrel of a rifle (or cannon) can achieve so trying to attain maximum velocity is sort of a waste of effort. Very small caliber...and thus lightweight projectiles can break 2000 fps out of a practical handgun which can be useful for defeating body armor...but IMHO little else.

Hydrostatic shock effects seem to require mid 2000's at a minimum to be effective and the recoil/blast of delivering such out of a handgun would compromise the usefulness of the platform. If you need such velocities...use a rifle. Handguns work well at delivering relatively heavy projectiles at moderate velocities which retain enough momentum to penetrate effectively which is their primary wounding mechanism.

I've got an Encore in 30-06 and while it's technically a pistol (15" barrel) it's quite a bit behind any 22-24" normal rifle in velocity production while the blast is significantly more dramatic than any normal magnum handgun which makes it a challenge to shoot accurately. It really kind of blurrs the line between rifle and pistol and is closer to the former than the latter and while it can exceed 3000 fps with very lightweight projectiles...they are of little practical use besides vaporizing the smallest varmint type critters.

 

[Cannibul]

186,000 miles per second.

That's as fast as anything can go.

 

[Flechette]

Ok, what about the practical limits?

If we had a .357 Mag chambered revolver could we get a useful increase in velocity if we made the cylinder walls much thicker? Let's say 1/2 inch between chambers. If we doubled the pressure would it be worthwhile or would it get a couple hundred feet per second more?

 

[barnbwt]

Maybe set off a claymore in your outstretched hands while wearing really good vest & gloves?
I'll bet high explosive could be done in such a small format, but there would not be a barrel (just a shaped charge) and the concussion would scramble the brains of the shooter, regadless of bulk recoil.

I personally think polymer-based squeeze bore systems (jacket that acts like a permanently attached sabot around a hard core) in a smooth bore format would stand the best chance. Very efficient in both expansion ratio and frictional losses while being lightweight.

 

[barnbwt]

Ok, what about the practicallimits?

Above a certain pressure/temp powder won't burn efficiently, so cramming more in a case is a very diminishing return.

 

[RX-79G]

Ok, what about the practical limits?

If we had a .357 Mag chambered revolver could we get a useful increase in velocity if we made the cylinder walls much thicker? Let's say 1/2 inch between chambers. If we doubled the pressure would it be worthwhile or would it get a couple hundred feet per second more?

Most manufacturers decided .357 Maximum was not practical due to flame cutting. It added nearly 300 fps over .357 Mag.

https://en.wikipedia.org/wiki/.357_Remington_Maximum

Barnbwt's point about case volume is a big part of this, too. Smokeless powder doesn't detonate like an explosive, it burns, creating an expanding gas. This is important in overcoming the inertia of the bullet and providing thrust continually down the whole bore. The Light Gas gun takes the concept a step further. There is no powder that is going to burn the way we need it to if you cram too much of it in the cartridge - it will just detonate.

 

[J-Bar]

The PRACTICAL limit? I think we are there...

I saw a fellow at an indoor range with a S&W .500 Maggie. I watched through the window in the showroom. He hit a silhouette at 15 yards about one shot in 5. I think he had reached his limit. The folks in the room with him reached theirs about the second shot. He finished alone on the firing line.

 

[Mauser lover]

186,000 miles per second.

That's as fast as anything can go.

Assuming that the speed of light in a vacuum is constant... Which we aren't quite sure about. If we can accelerate something long enough, we should be able to get it pretty fast, and there is always the possibility that Einstein was wrong about light being the fastest thing in the universe. If we could somehow get something that was propelled by light, we could have an extremely fast eventual velocity, but it might take quite a bit of time and distance to get there, and power. If you think about it... Turning on your Mag-Lite doesn't have much recoil.

So... Practically, .357 Mag is about going to do it! When we get decent railguns or whatever they call them... We'll see! If my relatively uneducated guesses are correct, if we can accelerate something with electricity we can come very close to the acceleration of light. It will probably take a while, and maybe not even in this generation, but that is probably what they told the Wright brothers! So... The speed of light is probably out of reach for a while, but who knows! We might find something faster. 'Tis the nature of science!

 

[RetiredUSNChief]

First of all, gun powder and modern smokless powders are not "explosives". Well...actually black powder (gun powder) is classified as a "low explosive" and smokeless powders are not classified as explosive at all.

From http://www.newworldencyclopedia.org/entry/Gunpowder

Some definitions say that gunpowder is a "low explosive." This is correct for black powder, but incorrect for today's smokeless powders, which are not explosives. If smokeless powder is burned in the open air, it produces a fast burning smoky orange flame, but no explosion. It burns explosively only when tightly confined, such as in a gun barrel or a closed bomb.

The United States Interstate Commerce Commission (ICC) classifies smokeless powder as a flammable solid. This allows shipping of smokeless powders by common carriers, such as UPS. In fact, gasoline is a more dangerous substance than smokeless gunpowder when the powder is unconfined (as opposed to being confined in a gun charge or in a bomb).

Black powder, however, is a true low explosive, and burns at almost the same rate when unconfined as when confined. It can be ignited by a spark or static electricity, and must be handled with great caution. Thus it is considerably more dangerous than smokeless powder, and is classified by the ICC as a class-A explosive; consequently, shipping restrictions for black powder are stringent.

Because the burn rates of these powders are, relatively speaking, significantly lower than true explosives, there are limits to how fast they can push a bullet. You can increase the velocity of the gasses produced by changing the shape of the cartridge (and thus the firing chamber) to take advantage of Bernoulli's principle. This has to do with the change in pressure and velocity across a venturi...in this case, the venturi created by necking down a cartridge to a smaller diameter than the body of the cartridge.

These effects on bullet velocity are also subject to additional limitations based on barrel length, friction, bullet construction, and a few other things.

For example, using more powder will, in general, produce a higher velocity for a given barrel length...but only to a point. This is because the burn rate of the powder is (relatively) constant, which means if you use more powder you will have a longer powder burn period. If the burn period lasts longer than the time it takes the bullet to travel the length of the barrel (a function based on the maximum pressure generated by the burning powder), then the rest of the unburned powder at that point in time is simply venting from the barrel and no longer providing motive force to the bullet. In othervwords, your wasting powder which isn't being used to propel the bullet.

Now...let's say you do design a cartridge which will produce some pretty awesome velocities. The question becomes "will the bullet design hold up to this?" I was just reading about some wildcat cartridge designs for the .357 bullet. They were pushing velocities high enough that the bullets were unable to maintain their physical integrity in some cases.

This would be the case if you were to design a gun which were strong enough to contain the forces of true explosives. What you would get wouldn't be a bullet traveling at extreme velocities...it would be a short lived Lead plasma jet coming out of the muzzle. You'd have to redesign the bullet...but even so, it would have its own physical limitations.

Speaking of physical limitations...ever fired a large caliber magnum, either a handgun or a rifle? Let's say you've actually fired a 30-06 rifle with 180 grain factory loads. That's a respectable kick from the recoil. Now let's say you were somehow able to achieve the same velocities from a 180 grain 30-06 bullet in a handgun. I don't know about you, but that's not a gun I'd want to shoot.

Now, take that same 30-06 bullet out of a rifle at double it's standard factory velocity. Then triple...and quadruple...and ten times the factory velocity. Recoild would rapidly become unmanagable, to put it mildly.

So...how fast CAN a bullet be pushed?

Practically speaking, whatever the maximum velocities you see for a given bullet in a given gun is it, because you've reached the various combined physical limitations imposed by all these things I've listed...and more.

 

[hdwhit]

Let's assume that metallurgy is not a problem. Use a barrel with a 12 inch diameter and a battleship breech lock. No matter what the barrel will not burst.

This is an irrational assumption as no handgun with a 12 inch diameter barrel would be practical within this axiom system.

Further, to entertain chamber pressures of 1 million pounds per square inch is nothing mere fantasy.

I would ask that one of the moderators close this post on the grounds that is assumes physics that can only exist in an alternate universe.

 

[gsbuickman]

this is really a theoretical impossibility because there are soooo many variables to consider, and with every shell being different you'll never find a one-size-fits-all solution to the question

 

[230RN]

Well, not handguns directly, but on the principles involved, the Germans build a multi-chambered cannon to get around at least part of this problem:

https://en.wikipedia.org/wiki/V-3_cannon

As in / similar to:

The idea's been around for quite a while and I believe Jules Verne used a system like that in one of his books --can't remember which one.

I was going to post this picture of one of the cannon designs, but... ummm... well, ladies, don't click on it.

https://upload.wikimedia.org/wikipe...n-Haskell_multi-chamber_gun_1883.jpg?download

Terry, 230RN

Pic credits in Properties

 

[Tirod]

First Post Nailed It. The practical limit is recoil. If you can't stand up and shoot it, makes no difference how fast it goes.

 

[mjsdwash]

I think practical limits are around 6000. using an explosive would bring that up in theory to almost the speed of light, in a vacuum but a more logical thought would be near what artillery flack does. maybe 20,000 fps or so could probable be done

 

[Mauser lover]

Even with a limit of 6000 fps, we cannot get there fast enough for handgun-length barrels. Even a .204 Ruger with a twenty-something inch barrel is "only" going about 4000 fps. We need a different propellant, and we need less recoil in addition to having an insanely strong breech.

Humanity has gone from heavy arrows relying on lasceration to lead balls going faster to get penetration, with more energy; to smaller chunks of lead going even faster, to copper projectiles to get even faster, but the energy has stayed relatively stable, much more stable than velocities. A cap and ball revolver shoots a ball pretty slow, but it is heavy enough to do plenty of damage. A .357 mag shoots a pretty light bullet pretty quickly. Maybe even close to the velocity limit of our current propellants in a pistol barrel. Somehow, we will need a lighter projectile, and a faster propellant, so our recoil isn't deadly.

 

[Jim Watson]

One SF author armed his heroine with a Slichter rail gun. Even though it fit her purse, it figured out to about the power factor of a .338 Win Mag. I bet that put a run in her stockings when she fired it prone, as depicted.

Robert Heinlein deployed the "booster gun" of V3 type on the massive armor that cracked the defenses of New Jerusalem in 'Revolt in 2100.'

It was said that the molded charge of the caseless HK G11 was a "denatured explosive" instead of the usual NC-NG-NQ propellant. Composition not given anywhere I saw.

Although smokeless powder is characterized as a propellant, the British used block Cordite in demolitions.
There was a local legend that some of the Good Old Boys put a blasting cap in a can of Bullseye (then 40% NG) and got it to go high order, converting a stump into a crater.

 

[jrmiddleton425]

In answer to this question, theory gets smacked down by the reality of what *is*.

For a 12-inch bore as stated in the OP, Wyoming-class batlleships mounted 12"/50 Mk 7 to Mk 18 guns during the time period 1912-1945.

The chamber volume is 11,863 cubic inches. The working pressure is 17.5 tons per square inch. What this shakes out to, is that a 335-pound charge of SPD propels a 740-pound shell to 3,000 fps at the muzzle.

If we use .204 Ruger at 4000 fps as an example, it is evident that the practical limit of the velocity of a projectile propelled by gunpowder is 3000-4000 feet per second.

12-inch gun data: http://www.navweaps.com/Weapons/WNUS_12-50_mk7.php

Edit: This gun weighs 124,000 pounds, plus or minus 200 pounds. The recoil is 36 inches. The rammer is driven by a 40-horsepower motor. This isn't something you can shoot offhand.

 

[cheygriz]

The sabot round in a smooth-bore 120mm gun on an M1 Abrams gets 5,000 FPS. That's the highest practical limit with today's technology.