This is the M16A4 Service Rifle.
To begin, as with any weapon, you will approach and treat it as if it were loaded.
Once you have confirmed it is not loaded and the weapon is "cleared", (by pulling the charging handle back and visually inspecting the chamber) we will commence with field stripping the weapon.
Step 1 - In the middle of the rifle, attached to the lower receiver, there are two pins. The ends of these pins are flat, and can be pushed out. Push out the pins.
Step 2 - Once the pins are removed, the lower receiver will be separated from the upper receiver. Pull back the charging handle, gently, and remove the bolt carrier group and charging handle.
Step 3 - Take the bolt carrier group, which looks like this
and remove the pin, (the pin is on the opposite side of the bolt carrier group in this picture). Once you do so, the firing pin, bolt, and carrier will be removed, along with a small and large pin. It looks like this disassembled.
This is the only picture i could find. Ignore the "extractor" parts mentioned, it doesnt pertain to what we're doing here.
So, as of right now, this is what you should have in front of you.
To clean, just apply a light coat of CLP, pictured below,
on to each of your broken down parts. Specifically, all areas of the bolt carrier group (bolt, firing pin, carrier) as well as the inside of the firing chamber in the upper receiver. Scrub lightly with something like a tooth brush, and then wipe clean with a rag. What you are doing here is removing built up carbon in the chamber and on the bolt carrier group.
Upon finishing, just simply reassemble and apply another light coat of CLP to lubricate the moving parts of the rifle and boom, youre done.EDIT - Barrel. Robert Sim
brought up a pretty good point. In the case of the barrel, there are two issues i didnt mention (this was your one chance Jon Davis
to upstage my answer).
1 - Depending on what you are doing with the rifle, rust can sometimes accumulate on the front sight post and around the tip of the barrel. This rust is easily removed with CLP and a vigorous scrubbing of the affected area.
2 - Cleaning the inside of the barrel. In circumstances where you use your rifle for more then just casual target shooting, you will have carbon build up inside the barrel as well. To remove this build up, use a long rod (stiff or flexible)*, with a small cotton swab attached to the tip. Slide/push the end of the cleaning rod down the entirety of the barrel and pull it through. This should allow for the cotton tip to remove carbon build up in the barrel.
*That's what she said!