They resumed production with the smaller and standardized 0.250 in pin in the mid-1990s. 12.

For other weapons colloquially referred to as AR-15, see AR-15 style rifle.

The AR stands for the first two letters of ArmaLite.

It was designed with the extensive use of aluminum alloys and synthetic materials in order to reduce weight.

Colts Manufacturing Company currently uses the AR-15 trademark for its line of semi-automatic AR-15 rifles.

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This example is fitted with an early waffle-patterned 20-round magazine.

It would still produce the AR-15 for police and military units though.

However, by May 2020, changed market conditions and a significant increase in demand allowed Colt to resume production for sales to private users.

The bolt carrier acts as a movable cylinder and the bolt itself acts as a stationary piston.

This mechanism is often called direct gas impingement (DGI), although it differs from prior gas systems.

Designer Eugene Stoner did not consider the AR-15 to be a conventional direct impingement mechanism, but that is how it came to be characterized.

The gas expands into the port and down a gas tube, located above the barrel that runs from the front sight base into the AR-15s upper receiver.

Here, the gas tube protrudes into a gas key (bolt carrier key), which accepts the gas and funnels it into the bolt carrier.

As the bolt carrier moves toward the butt of the gun, the bolt cam pin, riding in a slot on the bolt carrier, forces the bolt to rotate and thus unlocks it from the barrel extension.

Once the bolt is fully unlocked it begins its rearward movement along with the bolt carrier.

As soon as the neck of the case clears the barrel extension, the bolts spring-loaded ejector forces it out the ejection port in the side of the upper receiver.

The buffer spring begins to push the bolt carrier and bolt back toward the chamber once it is compressed sufficiently.

A groove machined into the upper receiver guides the bolt cam pin and prevents it and the bolt from rotating into a closed position.

The bolts locking lugs push a fresh round from the magazine as the bolt moves forward.

As the bolts locking lugs move past the barrel extension, the cam pin twists into a pocket milled into the upper receiver.

This twisting action follows the groove cut into the carrier and forces the bolt to twist and lock into the barrel extension.

Thus one upper receiver can quickly and easily be substituted for another.

Upper receivers are available with barrels of different weights, lengths, calibers, and rail systems with various sights and accessories.

Although, both shorter 16-inch (410 mm) carbine barrels and longer 24-inch (610 mm) target barrels are also available.

The lower receiver also contains the trigger, disconnector, hammer and fire selector (collectively known as the fire control group ).

Full-sized rifles use a fixed buttstock, while carbines generally use an adjustable telescoping buttstock.

In 1966 the company replaced the front pin with a paired nut and screw hinge using a 0.315-inch (8.0 mm) diameter pin to prevent shooters from being able to change receivers with military rifles or competitor rifles without the use of an adapter.

They resumed production with the smaller and standardized 0.250 in pin in the mid-1990s.

Pre Ban Colt Ar 15 Serial Numbers