The SAW is a select fire receiver based rifle usually equipped with a high-capacity magazine and, in most cases, will have a belt-fed system. The purpose of a SAW is to provide sustained covering fire for a squad of troops on foot.

The designation SAW may be outdated and the more objective Light Machine Gun (LMG) is currently in use. This is true for the M249LMG, in service under the USMC since 1989.