A lot of the civilian AR15s will shoot both rounds. The original manufacturer of the AR15 for the military was Armalite which later sold all of the rights to the AR15 to Colt.

Colt Manufacturing is one of the highest quality AR15's on the market. They have been building the assault rifle for a long time and perfected this gun. They ran into some trouble with labor strikes and suffered from some quality issues in the 1980's. They lost the U.S. military contract and had to refocus its efforts. Since the restructuring Colt came back on the market with the 1911 pistol and the AR15.

Heavy competition has sprung up in the AR15 market. There are many manufacturers such as Bushmaster AR15, DPMS, Rock River Arms AR15, Stag and Olympic. Bushmaster surpassed Colt for AR15 sales in the civilian market. They have cheaper AR15s offered in there line, but Colt has still sold its quality line of AR15s.

The AR15 is much like the First model T's Ford produced. It has uniform parts and can easily be broken down and rebuilt. Many different types of 'uppers' can be installed quickly and easily with just 2 pins. They range from .22 uppers to .50 cal uppers. Many of the favorite conversion are the 9mm and .45 caliber uppers.

Along with many different calibers you can get just about any length barrel you want. Some stats allow super short barrels.