The .357 Magnum, introduced in 1935, held the 
distinction of being the world's most powerful 
handgun cartridge for quite some time.  Even 
shooters of the big .45 auto are impressed with 
full-power .357 Magnum loads.  Only a few 
commercial cartridges, all but one being larger 
in bore, offer more energy at the muzzle.

    The cartridge was developed from the 
.38-Special.  Outward dimensions are identical, 
except the Magnum case is .135-inches longer.  
This slight increase is not necessary to achieve 
the .357's ballistics... the .38 Special case has 
quite enough volume for that.  Rather, it is to 
keep .357 Magnum ammunition from fitting into 
.38-Special handguns. Magnum cartridges develop 
around two-and-a-half times more pressure than 
.38 Special rounds and a handgun has to be 
specifically designed to handle them.

    Just as the .38 Special was "stretched" into 
the .357, the Magnum was stretched (first by 
wildcatters, then by Remington) into the .357 
Remington Maximum.

    Current .357 Magnum factory listings include 
a 158-gr.  bullet at 1235 fps with 535 ft-lbs. of 
energy, all at the muzzle of a 4" barrel.