The Ultimate Combat Round

[GunTech]

As noted, awating something like the new carbon-nanotube based supercapcitors. Not that ET and ETC weapons relay on plasma stimulated working fluid - sometimes in conjunction with chemical propellants (ETC). PSWF expand at a rate much faster than chemical propellants as well. There a reason why you don't see velocitie much over 4000 fps. The theorertical max rate of propellant gas expansion is under 6,000 fps, and realistically under about 5,000. PSWF don't have this same restriction.

In any case, I was amazed at how little power ETs actually require, since you are only converting a small amount of working fluid into plasma - typically about 5%. And being able to 'throttle' the pressure means you can match the pressure profile of the barrel. Ig battery technology ever becomes light enough and cheap enough, you could dispense with propellant and use something like water. I'm not sure there are any useful military applications, but it an interesting though - you could vary your by changing the electrical pulse - just dial the power up or down.

At this point, we are really getting into speculative stuff. I don'y see anything like that in the near future. Caseless, if it ever comes, will be first. And it looks like the military is favoring railguns over ET and ETC research these days.

 

[Anteater1717]

7.62x45

 

[PercyShelley]

At this point, we are really getting into speculative stuff. I don'y see anything like that in the near future. Caseless, if it ever comes, will be first. And it looks like the military is favoring railguns over ET and ETC research these days.

Any gun that relies on a working fluid to propel the missile will be limited by the speed of sound in that working fluid. Using HAN as a monopropellant or ETC would give you better performance than conventional gunpowder because the reaction products are lighter and therefore have a higher sound barrier. It's a similar problem to wringing specific impulse out of a rocket really.

The best working fluid would be pressurized monoatomic hydrogen; but show me the barrel material that could stand up to that again and again.

Railguns have a much higher fundamental speed limit; c as far as I know. I don't think that they're as energy-efficient as ET propulsion, but when you're desired end product is a ground-based hypervelocity ASAT or ABM weapon, energy efficiency can take a back seat.

I agree, however, that this is all pie-in-the-sky for those of us without extensive home laboratories and powerful capacitor banks. For the rest of us, there's http://www.powerlabs.org/ .

If we limit ourselves to more proven technology, how much could be gained by electrical ignition? It occurs to me that the primer has to be some sort of limiting factor on case pressures, and that the time between pulling the trigger and the hammer coming down affects accuracy.

 

[zinj]

I think the jump from metallic cartridges to caseless ammunition is too great a leap for right now. Rather, why hasn't serious research been applied into following the shotgun shell's lead and switching to plastic cases?

They are cheaper and lighter than brass, yet don't have the drawbacks of caseless ammo. Plus the technology is already well established; I'm sure a working design could be produced in less than a year by a committed team.

Evidentally one company did try this (NATEC), producing plastic cased ammo with a brass base. However, I would go for an all plastic design, like Activ shotgun shells*. This would be cheaper to manufacture, and weigh even less.

The benefits of this ammunition would be great. If the same cartridge design was kept the ammunition would function in all guns currently in inventory, while allowing more ammunition to be carried. If you went the other direction and upgraded weapons a new cartridge could be developed that was more effective than the previous issue yet weigh the same.

*The brass base on modern plastic shotgun shells is purely decorative. On paper shells it served the purpose of sealing the chamber, and helped to prevent the power burning through the hull when fired (hence the association of "High-Brass" with greater power.)

 

[GunTech]

Shotguns work at significantly ower pressure than rifles. You'd need a plastic that had the strength or ordnance brasse. Not saying it couldn't be done, but it would take work.

I tried the 223 half plastic cases in my AR, and had all sorts of problems. I don't know if it's the case, or the loading, but they weren't reliable. A stub case should work - with a plastic body and a brass base for obturation and to stand up to the extractor.

Of course it's not reloadable, and I don't think it was significantly cheaper at the time. That might be different now.

 

[Tony Williams]

Plastic cases are being tried as an alternative to the caseless rounds in the LSAT project. They are entirely plastic, and telescoped (the bullet is buried within the case). However, they only deliver a 33% saving on weight rather than 50%, and are bulkier.

You can have all-plastic versions of revolver ammo (they exist) but not of conventional self-loading rifle ammo, partly because of the pressures but mainly because the rim can't be made strong enough to resist being ripped up by the extractor as it tries to yank the fired case from the chamber. You need a different kind of gun action to handle all-plastic cases.

 

[Nolo]

Here's something:

Knox Engineering Company (or Corporation, I can't remember) is developing (or has developed, I'm not sure how far along they are) a powder that uses only 1/3 the weight of normal propellants. Basically this means that a cartridge like the 5.56 can be *gasp* straight-walled! Yes, they figured out pressures and everything (GunTech, that's why I asked you for the 3000 f/s 6mm cartridge) by telescoping the round (i.e., a small charge in the base pushes the bullet [and, in this case, some of the charge] forward before the rest of the powder fires to create a bigger chamber). Thus, I created the 5.56 Firebrand:

which has the bullet (a 90-grain) buried in the case (which is the same diameter as the original 5.56) and sealed off with a plastic cap or crimp (similar to a shotgun shell). It should (though I haven't calculated internal volume) be able to push the 90 grainer to 3100 fps.
Oh, and if I'm not mistaken, this will give you a 30% weight saving. Also, it (the length) allows you to put the magazine in the grip of the rifle (the rounds are approximately the same length as a 7.62x25 Tok), greatly improving balance, and creating a "half bullpup".
By the way, thanks to raubritter for the info.

 

[raubritter]

A 90grn 5.56 would be great. A rifle with the magazine in the grip would be very useful, handy, and fast to reload.

 

[Nolo]

I'm about to render the 6mm (100 grain) telescoping improved round and I was wondering whether to use a 9.6mm diameter cartridge or a 10.5mm diameter cartridge.
Can anyone give me a suggestion?

 

[Nolo]

I rendered both.
Anyway, I have a question:
Do I need to modify the cartridge so than all of the powder is behind the center of the bullet? It's not a big problem, I'm just wondering if it's a problem.
Here's my 6mm carts:


The top one is short enough to fit in a grip magazine, but the bottom one would make for shorter magazines.
Which one should I keep? They're approximately the same power, I think. It's more difficult to do output calculations with a nonbasic area of powder.
Also, does anyone know if .30 Carbine is used in any grip-magazine loaders? At least comfortably (I think an Automag or Coonan did once, but boy, their grips are wide!).
Could you fit a 40mm long cart magazine in a grip? Comfortably?

 

[Nolo]

Updated to solve the powder-in-front-of-the-bullet problem:

At least I think it was a problem.
The blue stuff should be a lightweight sealant.

 

[Owen]

where does the sealant go?

 

[GunTech]

Instead of sealant, just make it a plastic sabot. It gets dropped once the bullet exits the barrel. Sabots resukt in much lower pressure, usually at the expens of accuracy (e.g. the old accelerator projectiles).


I don;t dount you can have more compact propellants, but I have real doubts about lower pressures. You need a certain pressure to achieve a certain velocity. If you can stretch out the time/pressure curve, you can have lower peak pressure, but you must have the same area under the curve to achieve the same velocity. You can't get around the physics. Let's just say I am dubious about the claims of Knox Engineering.

ET and ETC can get around this, but that is an entirely different, and not really practical solution. Modern smokeless propellants have been under refinelent for over 100 years, and yet no one has found a viable method to significantly alter the pressure/time curve, and if someone does, it will be huge news for the shooting industry.

 

[GunTech]

I always wanted to try 22 sabots in a 30 carbine case. I have no idea how to set up QuickLoad to simulate it.

Here;s 30 caliober compared to a 22 in a 30 caliber sabot. You get the idea.

 

[tinygnat219]

Ummm, it's been around since 1891, the 7.62X54R.

 

[Nolo]

@ owen: Good question. I was thinking about using a burnable sealant, but you'd have to make it so that it wouldn't interfer with the rifle (by gunking it up or such), and I was also going to shorten up the case so that there wasn't as much of it and so that the weight would be lower ('cause it's all just dead space).
@ GunTech: Telescoping solves the problem of pressure. Basically they made the powder burn slightly slower so that it would expand using part of the barrel as the chamber, thus creating enough of a space to not have high pressures. By the time the bullet exits the barrel, it's doing 3100 f/s, and the "delay" is miniscule as to be not noticeable.
As for the sabots, I still want a .22 calber barrel. I think we can get around it without sabots.
@ tinygnat: that was entirely irrelevant.

 

[Owen]

Hey Nolo,

in your search for velocity with manageable pressure, i have a question for you.

Why can a shotgun push a full ounce at 1300 fps, and 6000psi, when a 9mm can only push a 124 grain bullet that fast with 25,000 psi?

I have a hint. F=PA, F=ma.

 

[Nolo]

It's easy. The total force of the projectiles coming out of the shell is increased because the particles have more area in a shotgun shell (as opposed to a 9mm) to push off of. It's like trying to jump off a (taut) wire as opposed to the floor. You just get more energy.
I feel dumb for not trying to include that in my calculations.

 

[Tony Williams]

Nolo said: Telescoping solves the problem of pressure. Basically they made the powder burn slightly slower so that it would expand using part of the barrel as the chamber, thus creating enough of a space to not have high pressures. By the time the bullet exits the barrel, it's doing 3100 f/s, and the "delay" is miniscule as to be not noticeable.

GunTech has it right: its the pressure of the gas behind the bullet that generates the velocity: no pressure = no velocity. As he said, you might be able to flatten out the pressure curve so that the peak pressure, near the chamber, is lower, but that just means that the pressure down the barrel has to be greater to compensate, otherwise you'll lose velocity.

 

[Nolo]

They don't have no pressure, they just have acceptable pressures. And I'm not sure how they do it, but it seems viable to me.

 

[Owen]

I don't think I understand your analogy Nolo.

Yeah, the larger area of the shotgun wad means that at any given pressure, the overall force on the wad is much higher than it is on, say, a 9mm bullet.

The other side of the coin is that you can't make it too easy for the projectile to go down the barrel, or you won't generate any pressure. The combustion of smokeless powder is dependent on pressure. The higher the pressure, the faster it burns.

Note that shotguns use a very fast powder. Large bore rifles tend to use very slow burning powders. Mull over that for a bit.

Now, can you think of a way to to increse the resistance of the projectile as it goes down the bore? That should help to flatten out the pressure curve.

 

[Nolo]

The powder for the round as I understand it is a slow-burning one, based off and developed from powders used in 40mm cannons.as for increasing resistance, the original charge, which may or may not be made out of conventional powders, pushes the round past the powder to create an optimum chamber size, low pressure (50,000 psi), but still resistant. Essentially, it becomes no different from a 5.56 round at that point. You aren't accelerating (per se) the projectile, I'm sorry if it sounded like that, but the speed of the round does increase, from a push with the initial charge to full velocity instantaneously (relatively).
As for my analogy, you just explained it.

 

[Tony Williams]

You aren't accelerating (per se) the projectile, I'm sorry if it sounded like that, but the speed of the round does increase, from a push with the initial charge to full velocity instantaneously (relatively).

I don't understand that - what accelerates the bullet is pressure. The more rapid the acceleration, the higher the pressure you need to achieve it. To achieve full velocity anything like instantaneously would require enormous pressure, and that would blow up the gun.

 

[Nolo]

You are, but you aren't doing it gradually, is what I mean.
Sorry for the confusion.

 

[Monkeybear]

Very interesting thread. Its good to see people out there trying new things and trying to solve problems themselves.

I was also going to shorten up the case so that there wasn't as much of it and so that the weight would be lower ('cause it's all just dead space).

I have a little experience with reloading and and I was a bit alarmed by this statement. The .357 Magnum revolver round, after you have charged it with with powder and depending on your load, can have about half of the case empty. When you insert your bullet into the case you have to be careful and maintain your Over All Length because if your OAL is too small it means that the bullet is seated too deeply. The resultant increase in pressure can be very dangerous. The increase in pressure is caused by the decrease in case volume caused by your bullet seating depth. I'm sure its a slower burning powder your talking about for your rifle round but my point is simply- case volume doesn't just mean how much powder you can fit. Perhaps, if you have not already, you should read a few reloading manuals and spend some time on the reloading forum if you are going to design your own ammo. Anyone; please correct me if I am wrong.

Also I notice that you tend to quickly gloss over very complex problems.

And, yes, the internal mechanism was complex, but I think you could simplify it significantly if you redesigned the weapon.

Simplify it how? Redesign it how? I understand that this the purpose of this thread is not to debate the design of various rifles but as this statement was made as a rebuttal to the argument that rifles using case-less ammunition were overly complex I think you should either conceded the fact that they are extremely complex or qualify your rebuttal. I am sure anything can be improved if done differently but the trick is in "How?".

Telescoping solves the problem of pressure. Basically they made the powder burn slightly slower so that it would expand using part of the barrel as the chamber, thus creating enough of a space to not have high pressures. By the time the bullet exits the barrel, it's doing 3100 f/s, and the "delay" is miniscule as to be not noticeable.

Statements like this sound good but once again the interesting part is- "How?". Cars work by exploding gasoline mixed with air in an engine to produce power that turns wheels. Sounds good enough to most people but if thats the extent of your knowledge, your not really qualified to build a better car.

I'm not trying to bust your chops so please excuse any rough language. I like your zeal and willingness to learn but I think your starting to run before you can walk. i know you are young and don't have access to a large amount of resources but get some some books on reloading, physics, design, strength of materials, anything along those lines. Used bookstores and used books on Amazon are your friends. Start actually making bullets from proven designs, and working with those. Take lots of math/science courses until you graduate highschool and take as many as you can in college. Don't stop playing and tooling around with ideas, thats the fun part, but don't forget the math and science of "Why?" is the hard part.