From A Recent Law-Enforcement Bulletin:
CATASTROPHIC FAILURE OF SEMIAUTOMATIC HANDGUNS
The continuous reloading and chambering of the same round may cause catastrophic failure in semiautomatic handguns.
Current Information - The Security Force at the Los Alamos National Laboratory in Los Alamos, New Mexico, recently reported on the catastrophic failure of a semiautomatic handgun when it was fired. The internal explosion caused the frame to break while the slide and barrel separated from the weapon and traveled down range. No one was injured in the incident. An investigation revealed that security personnel were repeatedly charging same round of ammunition into the chamber.
Technical personnel at Glock, Inc. advise that repeated chambering of the same round may cause the bullet to move deeper in the casing, further compacting the propellant. When a normal cartridge is fired, the firing pin hits the primer, igniting the propellant. When the propellant burns, the gas pressure drives the bullet out of the case and down the barrel. However, if the propellant has been compacted, the pressure may increase beyond the gun’s specifications, causing the weapon to break apart. Sigarms, Inc.’s personnel confirm that reloading the same round five or six times will cause problems, noting that reloading the same round even once will void their warranty. Both manufacturers stress that the prob-lem is not with the gun, but with chambering the same round repeatedly...
(I don't believe that the powder needs to be compacted for this phenomenon to occur - it should only require that the available space inside the case be reduced.)
Stephen P. Wenger
Firearm safety - It's a matter
for education, not legislation.