The AR-15 started life as the AR-10, designed by Eugene Stoner, Robert Fremont, and L. James Sullivan of the Fairchild ArmaLite Corporation. The AR-10 was chambered in .30-06 and later modified to accept 7.62mm NATO rounds. The AR-15 was developed to be a lighter, .223 / 5.56 NATO version of the AR – ArmaLite 10. ArmaLite sold the rights for the rifle to Colt in 1959. Colt marketed the AR-15 rifle to various military services around the world, including the U.S. with varying results. The AR-15 was eventually adopted by the United States military under the designation M16.
In 1960, General Curtis LeMay was so impressed by a demonstration of the ArmaLite AR-15 that when he was promoted to United States Air Force, Chief of Staff, he requested 80,000 AR-15s for the Air Force. In 1962 the U.S. Army special operations units started using the AR-15 later designated the M16 for special operations in Southeast Asia. Service members reported to have liked the stopping power of the light weight rifle in reports back to the rear. In January 1963, Secretary McNamara received reports that M14 production was insufficient to meet the needs of the armed forces and ordered a halt to their production. The AR15 was the only rifle that could fill the requirements of the U.S. Military. In 1982 the M16A2 was officially adopted as “U.S. Rifle, 5.56mm, M16A2”
The AR15 is an air cooled, gas operated, semi-automatic, automatic, magazine fed, shoulder fired weapon. Later A2 versions were upgraded with round hand guards, an easy rear sight adjustment ‘dial’ and the M16A2 fire selector lever auto selection had been replaced with 3 round burst. Eugene Stoner had implemented a unique modular design that that gave the rifle much flexibility. You can get 7 ½ inch through over 24 inches long barrels ranging in calibers from .22 through .50BMG. The direct gas system does not use the then conventional piston and rod instead it uses the gas tube to feed gases into the receiver. The magazines range from 10 thru 40 double stacked rounds to 100 round drums.
This is a very practical firearm because of its modular design. To me that means that you can purchase one weapon and use the accessories you need to meet your needs for a particular mission. Be it, hunting, home defense, or just at the range plinking away. The AR15 will suit your need like no other firearm can.
Field Stripping can be done with what everyone should have out in the field, a bullet. Might not be the best tool, but in a pinch it will do everything you need to do. First thing you need to do is to remove the magazine, clear the weapon, ensure the bolt carrier group is forward and the safety is on. Set the firearm so the barrel is pointer to the right. Push the rear take down pin towards you, it will not come all the way out and you should feel the upper and lower separate when it is pushed far enough. Now do the same for the front take down pin. You can now separate the upper from the lower receiver.
To disassemble the upper receiver pull the charging handle back and remove the bolt carrier group. The charging handle will drop down as you continue to pull and can be removed from the receiver. On the left rear side of the bolt carrier, you’ll see what looks like a cotter pin, this is the firing-pin retaining pin. Pull the pin straight out and the firing pin will drop out of the bolt. Turn and remove the cam pin the bolt will now slide out. Make sure the gas ring gaps are not lined up and are in good shape. Next remove the extractor pin, the extractor will then come out. Inspect the extractor assembly spring and rubber piece to ensure good working order. Clean everything up with a small cleaning brush and solvent then wipe down with CLP. Re-assemble the bolt by putting the extractor and spring assembly back in the bolt and inserting the extractor pin, return the bolt to the carrier and insert the cam pin and rotate, insert the firing pin and the retaining pin. Run a couple swabs with solvent followed by CLP down the barrel. Insert the bolt group and charging handle to the upper receiver.
The lower assemble contains the trigger group, buffer system and the stock. To remove the buffer and spring, push in on the buffer and depress the retainer pin. The buffer and spring will come out. Clean the buffer assembly, spring, and tube with a swab dampened with CLP. The trigger assembly will require some grease at the pivot points. Inspect the stock for cracks and other damage.
The AR-15-style firearm is a versatile, modular, and easy to maintain rifle that with a little maintenance will last you a very long time.
U.S. Army TM 9-1005-319-10