How would you make a gun like this?

Question

If a person were to walk over one of a power plants pipes which contain the extremely hiehg pressure steam in which generates electricity they would be cleanly cut in half.
This got me to wondering is there any convinient way to make a gun that could use absolutely nothing besides tanks that you fill up before the use of the gun, didn't wiegh much more than heavier modern guns used today, and was without question lethal?
Well I don't mean to answer my own question but duh you can. A simple pump up BB gun is most the time lethal.
But eliminate the projectile and leave only the air to reach a target and kill. Would it be possible, what might you need for such a thing, and finally how far could this thing shoot before mixing with the rest of the air becoming worthless?
Sorry for having such a long question :-)
Thanks.

Answer 1

. Such a gun would be difficult or impossible to make. Friction with the other air would cause your project stream flow to become turbulent very quickly. Special nozzle design could improve the length over which the high pressure flow held together, but getting the flow to hold together for 20 nozzle diameters would be something which has never yet been accomplished. That would mean that a 1 inch diameter nozzle would produce a flow which was no longer tightly focused 20 inches from the gun. And, to produce such a high pressure with any useful amount of air, the gun would have to have a very heavy walled pressure tank.
. Where air charge guns are used to some effect, the inoculation of large groups of people, like in the Army, pressurized air is supplied by a hose from an air compressor or a pressurized air tank. This is not a very portable system.

Answer 2

Well, it wouldn't reach far. You only need about 1000 psi to cut the skin. As many have found out at the local car wash. The problem is that the jet of air at high velocity is turbulent and will quickly mix with the surrounding air and loose its velocity.

I would say something small enough to carry would only have a lethal range of a few inches.

Answer 3

I SAW ON HISTORY CHANNEL WERE THE NAZI'S HAD MADE A GIANT AIR GUN THAT SENT A AIR BLAST TO TRY TO BRING DOWN AIRCRAFT, TO TO THIER DOT COM
AND LOOK FOR IT, I SAW IT SOME TIME AGO, I BELIEVE IT WAS TITLED WIERD
WEAPONS OF WW2, GOOD LUCK