The AR 15 is the most prominent assault weapon used by private citizens of the United States. One reason is that the weapon is largely based on the military’s standard issue rifle, the M 16. The weapon is detachable into two sections, the upper and lower, making it an incredibly modular and flexible weapon. This article discusses the AR 15 upper in more detail.
An AR 15 upper contains none of the parts that normally are regulated as a firearm, namely the trigger group and hammer. The upper primarily consists of the barrel itself and the gas block assembly mechanism that helps channel the energy from the explosion to help reset the weapon. As a result, the AR 15 upper is not regulated by federal firearms laws and can generally be mail ordered most places throughout the United States without registration, filling out any papers, or special handling instructions.
As a result, these are very popular accessories for hobbyists who often save money by buying a cheap lower or an even cheaper assembly kit for a lower, and then buying an upper to complete the rifle. By just buying different uppers with varying barrel lengths and chambered for different rounds, one can effectively own a number of different assault rifles, for a lower price. If you buy the lower privately at a gun show, you will not even have to report any of them to the government.
An AR 15 for sale comes with a variety of barrel lengths. 16″ is the minimum that can be legally purchased without a special license in the United States. This has the advantages of portability and ergonomics, and is closer to the 14″ M-4 carried by many troops in combat. The 20″ barrel is a more standard barrel length which comes with increased distance and accuracy. For long distance target shooters, a 24″ barrel will deliver the greatest precision and firepower.
A wide variety of calibers can be delivered through an AR 15 upper. The most common is the .223 caliber which approximates in dimension the standard NATO round used in M 16s. Many people will buy uppers chambered in 22LR as target practice rifles these days as the price of ammunition has skyrocketed and 22LR tends to be the cheapest and most available rounds. There are a variety of specialized calibers believed to deliver superior performance such as the 6.5 Grendel with a high ballistic coefficient and the 6.8 Remington SPC which provides more firepower. One can even get an AR 15 upper chambered in Russian 7.62 x 39 calibers.
There are a wide variety of AR 15 uppers available to chose from depending on your shooting habits. However, due to the re-election of a very ardent foe of the second amendment in the United States, you might consider getting one of these weapons before it becomes a crime for someone to sell one to you.