Assault Weapon was a multitude of designs for the production of a "medium" caliber of individual troop weapon. Unlike battle rifles that are chambered in large high power calibers, such as 7.62x51mm, 30-06, 7.62x54r, 8mm mauser, etc. These rounds were scaled down in power level and evolved into 7.62x39mm, 5.56x45mm and other less common variants. These weapons were designed for select fire capability to enable troops to deploy a large amount of projectiles while engaging in tactical movement. Typically, traditional battle rifles were not utilized in full auto because of the lack of control/accuracy and were relegated predominately as a Squad Automatic in a much heavier platform to enable suppressive fire. The advent of the Assault weapon allowed a more controllable and portable select fire weapon to be employed by each individual troop in a post trench warfare combat style. The tactics employed with assault weapons has been to provide suppressive fire to enable other troops to move while the enemy is taking cover from the suppressing fire. The key take away here is that an assault weapon IS a select fire weapon. Any semi-auto version is not an "assault weapon" by definition. If it does not have select fire capability, it does not fulfill the primary purposes and capabilities of a military assault weapon. This is not to say that it is benign, it still has significant capabilities as a firearm, however it has more in common with the qualities of a traditional battle rifle.

It is a rifle that can fire either automatically or semi-automatically and is chambered for what is termed a "medium-energy" cartridge. The early German examples were noteworthy for having pistol grips. Ever since, it seems to be applied to long arms with pistol grips.