We know all about the legendary status that Ma Deuce has. It's served for over eight decades, and has shot down planes, mowed down terrorists, among a host of other missions.
That said, Ma Deuce didn't become a legend on its own. When you look at it, it's just a big, metal object by itself. It can't target the enemy, much less fire, on its own. To work, it needs to have someone load the belt, chamber the round, aim it, and pull the trigger. In other words, Ma Deuce is nothing without a well-trained soldier, Marine, airman, or sailor manning it.
That said, you can't just hand the guns over to those folks and expect them to use Ma Deuce (or any other weapon) to its maximum potential. That takes training and practice. And for all the advances in computer technology, you just can't beat going to the range and putting real bullets downrange.
This just doesn't apply to Ma Deuce. The M240 is much the same way. Based on the FN MAG, a medium machine gun chambered for the 7.62x51mm NATO round. This is a much newer gun than Ma Deuce, and has largely replaced the M60 machine gun that saw action in Vietnam and Desert Storm, among other conflicts.
According to FN's web site, the M240 is 48.5 inches long with a 21.7 inch barrel. It can fire up to 650 rounds a minute. Usually the teams come in two, with a gunner and an assistant who also carries the ammo, although in some cases, and ammo bearer is added to the machine gun team.
You can see a video of Army Reserve soldiers training on these two machine guns below.