Similar to doing a Half Cocked on a wheel gun is the hammer down on a .45 colt. Many people (including police and former military) don't like the full cocked and locked position so they will rest the hammer by lowering it down on a live cartridge. Yea .. I go nuts when I see this ... drop the firearm and bam it goes off. They just bypassed all the safety mechanisms that worked for 95 years without fail.