unobtanium gun

[SteveS]

I had a thought about a different sort of ultra-tech gun. Instead of an advanced means of propulsion (magnetic, etc.) or an energy weapon, what about an ordinary design with advanced materials? If the chamber and barrel were made to some ridiculously strong material, able to withstand enormous chamber pressure, what kind of slug-thrower could one build? Would such a thing allow Gauss rifle velocities with ordinary propellant? Would a high explosive propellant allow more compact cartridges? Would caseless ammunition be practical?

[Fred Brackin]

Originally Posted by SteveS

I had a thought about a different sort of ultra-tech gun. Instead of an advanced means of propulsion (magnetic, etc.) or an energy weapon, what about an ordinary design with advanced materials? If the chamber and barrel were made to some ridiculously strong material, able to withstand enormous chamber pressure, what kind of slug-thrower could one build? Would such a thing allow Gauss rifle velocities with ordinary propellant? Would a high explosive propellant allow more compact cartridges? Would caseless ammunition be practical?

"Travekller" and "ridiculously strong material" usually leads you to "bonded superdense". That material is 2x as dense as steel but 14x as strong as armor. That's probably enough to withstand detoanting high explosive. You'll need a projectile of bonded superdense too.

The limit for velocity would be the detonation velocity of the explosive/propellant.. That's 8000 meters per second for common 21st century HE but 10,000 and even 15,000 is beleived to be possible.

Do you want a projectile that goes that fast? Probably not. We're talking about meteoric velocities and your projectile would burn up in atmosphere and/or explode like a meteorite and make wide but shallow craters upon striking a solid object.

Bonded superdense would probab;ly be better than any material known to us though. Assuming that its' molecular bonds are 14x as strong as steel those bonds could probably handle velocities equal to the square root of 14 (because kinetic energy increases as the square of velocity).

I can not tell you exactly what the velocity where steel begisn to fail is. It's certainly lower than the 1600 meters per second of modern tank guns but might be around the 1000 meters per second seen in WWII tank guns. It's a nice round number anyway.

So the square root of 14 is 3.74 so we might be talking about 3740 meters per second for a bonded superdense projectile that would still pentrate like asolid object. This would also be the number for Gauss weaposn firign bonded superdense.

Now you might wonder how projectile damge goes up with velocity in Gurps? The answer is directly. That is to say that while kinetic energy goes up with the square of velcoity, damage goes up with the square root of KE.

So take the velocity in meters per second of any round you have damage for in Gurps. So 7.62 NATO has a velcoity of 850 meters per second and does 7D. Divide 3740 by 850 and you get 4.4. multipl 7D by that and you get 30.8. You could round up to 31 or say that your bonded superdense bullet of the same diamter was just a little bit lighter thna the 7.62 NATO and settle for 6Dx5.

You will have 4.4x the recoil too so maybe you've designed a battlesuit rifle. MinSt probably ought to be around a 21 ST. also remebr that you can almsot certainly do the smae thing with gauss and just make less noise.

[SteveS]

Interesting. One reason such a weapon might exist is that the manufacturer is on a world that lacks the ability to build the complex materials required for a Gauss weapon. They might also lack the ability to manufacturer bonded superdense, but importing comparatively simple components (barrels, projectiles) made of advanced materials might be economical compared to importing complete, complex weapons.

The recoil would be a problem for anything but a battlesuit or vehicle weapon. But would it make a man-portable recoilless rifle practical? It might work as a sniper rifle for people facing battle dress.