There are numerous misunderstandings about “machine guns.” Most of America think they’re capable of spitting out continuous streams of lead they way they often do in Hollywood movies. The reality is a bound by the laws of physics. And machine guns have a nasty habit of heating up when they’re run non-stop.
Check out the video below. In it, Devin Gude, runs 700 rounds through an M249 Squad Automatic Weapon. The shoot was designed to test a Silencerco SWR suppressor, a can that is rated for full-auto fire. The Silencerco didn’t do too well.
The former Marine gunner worked in the West Coast Armory in Bellevue, Washington, where the footage was shot. It was his last day, so he took to the range with the SAW to say goodbye in epic fashion. Someone beside him is feeding rounds through on long belts as the non-stop barrage of fire continues.
It didn’t take long for the suppressor on the end of the barrel to start glowing. The heat builds so much that the can on the of the barrel catches fire. This is entirely expected.
Overheating during constant fire is a problem with no easy solution. When the steel of the barrel heats up, its rigidity changes. It doesn’t behave like a cold barrel, and this results in a loss of accuracy.
If the barrel gets too hot, it can begin “cooking off” rounds in the gun. This means the rifle will fire, so long as it is functioning, without anyone pulling the trigger. This just adds more heat.
The eventual end is meltdown or catastrophic malfunction due to a round or rounds exploding out of battery. This gun handles the heat well, even though the barrel ends up glowing red hot. While the gun itself might come out OK, heating steel to that temperature and letting it air cool can anneal the steel, making it soft. While it looks good on the video, it isn’t recommended.
Gunners in the Army, who have used the SAW in Afghanistan, Iraq, Kosovo, and Bosnia, are all trained to fire in shorter bursts.
While this video makes the gun look appealingly cinematic, this type of abuse would be pointless in the field as it decimates what would otherwise be a very reliable firearm.