The weapon can fire guided and unguided projectiles up to 42 km (26 mi). Firing ballistic missiles, such as the U.S. Army Tactical Missile System—ATACMS, it can hit targets 300 km (190 mi) away; the warhead in such shots reaches an altitude of about 50 km (164,000 ft). The M270 can be used in shoot-and-scoot tactics, firing its rockets rapidly, then moving away to avoid counter-battery fire.
MLRS was developed jointly by the United Kingdom, United States, Germany, and France. It was developed from the older General Support Rocket System (GSRS). The M270 MLRS weapons system is collectively known as the M270 MLRS Self-propelled Loader/Launcher (SPLL). The SPLL is composed of 3 primary subsystems: the M269 Loader Launcher Module (LLM), which also houses the electronic Fire Control System, is mated to the M993 Carrier Vehicle. The M993 is a derivative of the Bradley Fighting Vehicle chassis.
The rockets and ATACMS missiles are contained in interchangeable pods. Each pod contains six standard rockets or one guided ATACMS missile; the two types cannot be mixed. The LLM can hold two pods at a time, which are hand-loaded using an integrated winch system. All twelve rockets or two ATACMS missiles can be fired in under a minute. One launcher firing twelve rockets can completely blanket one square kilometer with submunitions. For this reason, the MLRS is sometimes referred to as the "Grid Square Removal System" (metric maps are usually divided up into 1 km grids). A typical MLRS cluster salvo consisted of three M270 vehicles each firing all 12 rockets. With each rocket containing 644 M77 grenades, the entire salvo would drop 23,184 grenades in the target area. However, with a two percent dud rate, that would leave approximately 400 undetonated bombs scattered over the area that would endanger friendly troops and civilians.
In 2006, MLRS was upgraded to fire guided rounds. Phase I testing of a guided unitary round (XM31) was completed on an accelerated schedule in March 2006. Due to an Urgent Need Statement, the guided unitary round was quickly fielded and used in action in Iraq. Lockheed Martin also received a contract to convert existing M30 DPICM GMLRS rockets to the XM31 unitary variant.
The M31 GMLRS Unitary rocket transformed the M270 into a point target artillery system for the first time. Due to GPS guidance and a single 200 lb (91 kg) high explosive warhead, the M31 could hit targets accurately with less chance of collateral damage while needing fewer rockets to be fired, reducing logistical requirements. The unitary warhead also made the MLRS able to be used in urban environments. The M31 had a dual-mode fuse with point detonation and delay options to defeat soft targets and lightly fortified bunkers respectively, with the upgraded M31A1 equipped with a multi-mode fuse adding a proximity airburst mode for use against personnel in the open; proximity mode can be set for 3 or 10 metres (9.8 or 32.8 ft) height of burst (HOB). The GMLRS has a minimum engagement range of 15 km (9.3 mi) and can hit a target out to 70 km (43 mi), impacting at a speed of Mach 2.5.
A German developmental artillery system, called the Artillery Gun Module, has used the MLRS chassis on its developmental vehicles.
In 2012, a contract was issued to improve the armor of the M270s and improve the fire control to the standards of the HIMARS.