Do-It-Yourself/Field stripping m16

Clear the rifle and make it safe. To avoid accidental firing, always look into the chamber after clearing the weapon to make sure it does not contain a round. Also, stick a finger into the ejection port and into the chamber (you may need to use your pinky if your hands are large) to feel if there is a round in the chamber. This is the method taught by the USMC: "visually and physically inspect the chamber". This is a good habit to get into because the physical inspection acts as a nice check of the visual inspection, and it works when visibility is obscured (e.g. in the dark).

An M16 being cleaned in 1970.
1. Place selector level to safe (this can only be done when the weapon is cocked).
2. Remove the magazine by depressing the magazine catch, and pull the magazine forward.
3. Lock the bolt open by pulling the cocking handle to the rear and engaging the bolt catch.
4. Ensure that the selector is at safe and check in the chamber to make sure that it contains no ammunition. With the selector still at safe, press the upper half of the bolt catch allowing the bolt to go forward.
5. Place the selector to SEMI and squeeze the trigger to release the tension on the hammer spring.

Stripping

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Proper maintenance of an M16 is important.
1. Remove the sling if attached.
2. Stand the weapon butt upright on a firm surface and depress the slip ring at the chamber end of the hand guard.
3. Remove both sections of the hand guard from the slip ring and pull down to unclip from the foresight sleeve.
4. Use a pen to push out the two takedown pins located at the rear of the selector switch and the front of the magazine housing to separate the upper receiver from the lower receiver.
5. Pull back the charging handle assembly to remove the bolt carrier assembly.
6. Remove the charging handle by pulling back and down.
7. Move bolt assembly forward to unlocking position and remove firing pin retaining pin. Do not lose the firing pin retaining pin.
8. Push in the bolt assembly to put in the locked position.
9. Catch firing pin as it drops out of the rear of the bolt carrier assembly.
10. Give the square cam pin a quarter turn and lift out.
11. Remove bolt assembly from the bolt carrier assembly.

It is possible to strip the weapon further by removing the extractor and spring assembly. The buffer spring can be removed from the butt, but this is not normally done during daily stripping. Reassembly is a straight reversal of the stripping steps.