USMC Weapons Safety Rules:
1. Treat every weapon as if it were loaded.
2. Never point a weapon at anything you do not intend to shoot.
3. Keep finger straight and off the trigger until you are ready to fire.
4. Keep weapon on safe until you intend to fire.
A 5th rule was added later which says "know your target and what lies beyond."
Always imagine there's an imaginary tunnel between yourself and your intended target. The barrel of your weapon should always stay in parallel to that tunnel and the muzzle should never approach an angle which would break that plane. This is called 'flagging' which puts other people potentially in direct line of sight with your muzzle and therefore potential danger. You should be aware of this the second you are about to uncase your weapon.
Weapons conditions:
Condition 4:
No magazine inserted, no round in chamber, bolt/slide forward, weapon on safe, hammer down.
Condition 3:
Magazine inserted, no round in chamber, bolt/slide forward, weapon on safe, hammer down.
Condition 2: (does not apply to the M16 or M9 or many others)
For 1911 style actions only: Magazine inserted, round in chamber, bolt/slide forward, hammer down
Condition 1: (for all except 1911 style action)
Magazine inserted, round in chamber, bolt/slide forward, weapon on safe, hammer down.
For 1911 style action: Magazine inserted, round in chamber, bolt/slide forward, weapon on-safe, hammer cocked. Also referred to as "cocked and locked"
Condition 0: (not in current military usage, derived from LtCol Jeff Cooper's "modern method" for 1911)
Magazine inserted, round in chamber, bolt/slide forward, weapon OFF-safe, hammer cocked.
---------------------------------------------------------------
Most modern military personal only refer to conditions 4,3, &1.
4: No mag, completely empty, on safe. The most inert condition.
3: Magazine inserted, but still mostly inert. This is the stardard carry condition except when involved in direct combat.
1: Used to refer to any weapon with a round in the chamber. Typically only used when use is imminent. The safety is always on except when actually engaging targets. Marine Corps policy is to return the weapon to safe after engaging targets and before moving. This becomes automatic. Condition 2 does not apply to current issue weapons.
When most folks refer to Condition 1, they mean there's a round chambered, and if applicable, the weapon is on safe. This is not universal as there are many different models and action types to which some Conditions may or may not apply.
Before you get to a range and at anytime you finish you should be Condition 4 with the exception of being 'at the ready' in case of personal defense and degree of threat. Anytime you receive or pass off a firearm, you MUST drop the clip and visually inspect the breech to ensure no round is chambered and that the weapon is on safe when appropriate.
Failure to abide by these basic rules will result in me or your Drill Instructor beating your ass to a pulp or you shooting an innocent person and going to jail or shooting yourself and dying.
