What type of propellant would you need to create a round that

>>33981369
Ignoring cost and availability, the absolute cleanest burning fuel that would even come close to the energy density necessary would be cryogenic liquid hydrogen.

pure oxygen

>>33981394
Could you fit enough into an existing cartridge?

>>33981404
Would that produce enough power with what you can fit in a rifle cartridge?

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>>33981369

A pressurized mixture of hydrogen and oxygen contained by a scored burst disc behind the projectile, with a piezo igniter.

Or maybe the same idea with some other fuel, like propane or even powdered carbon.

>>33981413
No, based on my rough guessing, hydrogen would require double volume per unit energy compared to nitrocellulose.

Liquid methane would work, but there'd still be combustion residue and carbon fouling, albeit less than gunpowder.

Why'd I type methane?

I meant liquified propane/butane gas.

>>33981434
OP said "work", not have the same energy.

How far away from having magnetically propelled bullets from small arms?

>>33981455
I suppose it would be like airguns where you just shift your energy expectations for any given caliber. E.g., .30-.35 airgun roughly equals .22 LR.

>>33981369
I'm pretty sure nitrocellulose, completely combusted, leaves no residue. The problem is that completely combusted cellulose wouldn't be very energetic. Instead we pack it in and have inefficient but fast combustion to get the most bang possible.

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>>33981369

Very extremely compressed air


Bloke on the range did a video about these cartridges he gets in Switzerland where you pump up with air that work in firearms with lead (non jacketed) projectiles.

I guess the "primer" is like a valve or something that opens up and pushes the projectile out of the brass case

For semi autos you'd need a large volume of compressed air in a case to cycle though

>>33981455
The nature of combustion is such that if it's not stoichiometrically perfect, there will be carbon soot and char since most fuels are hydrocarbons. The only exception is pure hydrogen which has too many limitations and issues to even attempt.

I'm trying to work within the constraint of chemical combustion propellant when the obvious and much easier answer would be an electromagnet railgun powered by a nuclear reactor.

Is there something that could be burned, that would clear out the fouling of normal ammo?

Like when you shoot .22lr through a normal ar15. They suggest shooting a few rounds of normal 5.56 through to clear our the rim fire fouling.

>>33981369

Are we talking something that produces the pressures needed to propel a bullet all at once or something that builds up the pressure like how rifle powder burns slower than pistol powder?

>>33981500
There's still calcium impurities left over, even with a lean burn. Various oxide gases can react with atmospheric CO2 to form solid carbonates as well, but this is mostly a problem with a rich fuel-air mix.

>>33981532

I know in inline muzzle loaders you can fire just a cap through it and it'll blow any loose fouling out of the bore

You could probably do that with any gun really you just need a case with no powder or bullet

>>33981574
Whatever gets the round out to kill someone at 300+ meters

>>33981532
>burned
You mean detonated. Primer mix has a supersonic detonation velocity. and can blow out light fouling like >>33981589
said.

Physical ejection is easier, carbon fouling would require a lot of oxygen to attempt to burn. Liquid oxygen and a decent spark could probably cook off the residue but cryo and guns generally haven't been tried.

>>33981589
Just reload the primer on spent cases

>>33981585
Well, OP did say money was no object. There is no calcium in pure nitrocellulose.

Okay instead of clean burning let's think about alternatives to gunpowder all together, electronic, combustion or other alternatives.

>>33981656
Super critical water steam.

>>33981824
Super heated air. All you'd need is a very high power laser or electrical arc.