M240 Machine Gun

A number of designs of the period from various countries were considered, but it was narrowed down to the M60E2 and the FN MAG. They underwent a large testing, including the older M219 as well.
Two main criteria analyzed were "Mean Rounds Between Stoppages" (MRBS, jams that can be cleared within minutes) and "Mean Rounds Between Failures" (MRBF, such as a part breaking).

The results for the evaluated machine guns were the following:


A Seabee fires an M240B mounted atop a Humvee.

The test applies only to the 70s-era versions tested. That aside, for these types the clear winner was the MAG, which was designated as the M240 in 1977 after the Army competition.

It went on to replace many older types for the vehicle/coaxial role in the 1980s. The M240 proved popular enough that it would be adapted by the infantry later on, spawning the M240B and M240G.

The M240 would be adopted in the late 1990s by the Army for infantry, beating out the M60E4, which though lighter and cheaper did not offer commonality with the vehicle borne M240, other NATO FN MAG users such as Britain, or the USMC.
The various versions of the M240 have not yet entirely replaced all the M60 versions, though they have for most main applications and roles.
Variants


A Marine performs maintenance on an M240 pintle mounted machine gun, mounted on a LAV.



A M240B in use by a U.S. Army soldier.

The NATO version of the M240 is known as the MAG 58, in the UK it is known as the L7 General Purpose Machine Gun.

This has significant advantages in training, logistics support, tactical versatility, and joint operations. For example, an M240B's buttstock and bipod may be carried in a vehicle to enable the crew to convert the coaxial weapon to an infantry model in the event that they are forced to withdraw from an inoperable vehicle.