The conditions are most often used to refer to a single action semi-auto (1911 type) and describe the carry condition of the sidearm.
Condition 1: "Cocked and Locked"
The pistol has magazine inserted - one round in the chamber - hammer back (cocked) - safety engaged (locked). The preferred mode of carry for single actions like the 1911 and Browning HP.
Condition 2: The pistol has magazine inserted - one round in the chamber - hammer "down" (uncocked). This is probably the worst mode of carry for a single action like the 1911 and BHP. Old timers say condition 2 means you have 2 chances for an accidental discharge (AD)- one when you lower the hammer over the live round and one when you try to cock it. Most of the DA/SA semi-autos, however, are actually made to be used this way. The Beretta, for instance, has a "hammer drop" safety. When the safety is engaged it safely "drops" the hammer for you, over a blocked firing pin.
Condition 3: Magazine inserted - no round in the chamber - safety off - hammer doesn't really matter, up or down. When the time comes to use it you have to rack the slide to chamber a round. This mode can get you killed unless you practice it a lot. If you don't, you'll probably forget to do it or short stroke it and drop the hammer on air.
Sorry Grayfox - I was typing while you posted - your explanations are right on!
Mikey
[This message has been edited by Mikey (edited September 02, 1999).]