Mercoled“, 14 luglio 1993 15:07:26
          Mechanics Item
   From:          CompuServe
   Subject:       Bullets
   To:            Physics
How about this.  Gunpowder burns very hot and very fast.  This "explosion"
results in the rapid expansion of the gaseous by-products which accelerates
the bullet out the gun barrel. Very similar to the mechanism that drives the
piston of an internal combustion engine.  The pressure build-up behind a
bullet may be as high as 50,000 psi for a very brief moment.

A typical bullet velocity is 3000 feet per second.  Note this is several
times faster than the speed of sound (~1000 feet per second).