Something that's been puzzling me for awhile. Why does the US Army use a belt-fed machinegun as a squad automatic?
My best guess is that it's just tradition, an extension of the "horse cannon" concept, in which a team of men can move a tripod-mounted machine gun from place to place on a battlefield. Someone liked that concept so much, they decided to make it so that one guy could lug around a 30 pound LMG with a bipod, and a bunch of other guys in the squad could carry ammo.
I really cannot see any concrete benefit to using a belt fed system, though. You end up with a gun that's bulkier, heavier, more complex, and inherently less reliable. You have to train soldiers a different manual of arms. Because the soldier has to actually lug around the gun and ammo, there's a limit to how much ammo can be in the gun at one time. From what I've heard, in Vietnam the standard M-60 belt length was 50 rounds. Right now, most soldiers prefer the 100 round nylon pouches, since they're much lighter than the 200 round ones.
Sustained rate of fire? The time it takes to reload means there won't be a whole lot of difference there. Pull back operating handle, open cover, remove pouch, attach new pouch, tilt gun to the right, position first round, close cover.
If the cyclic rates of fire between a mag fed and belt fed gun were equal, let's say 10 rounds per second, and it takes 2 seconds to swap a mag, 5 seconds to change belts, that gives an actual maximum rate of fire of 360 rounds per minute for a gun which uses 30 round mags, compared to 400 rounds per minute for a gun that uses 100 round belts. Not a heck of a lot when the belt fed gun weighs twice as much.
Ammo weight, once again there's little difference. 300 rounds in magazines weighs 10.7 pounds. 300 rounds in linked, pouched ammo weighs about 10.0 pounds.
About the only benefit of the M249 in particular is it fires from the open bolt so it cools faster, and has a higher rate of fire. And the weight might help with the recoil (inasmuch as 5.56mm has recoil, even in full auto). But what's the benefit over a magazine-fed M16-based LMG, which fires from an open bolt at a higher cyclic rate, uses larger capacity magazines (maybe decent quality drums), and has some weight added (steel receivers would be a good start)?
It seems like the Russians came to the same conclusion as me, as they saw fit to replace the RPD with the RPK in the squad automatic role (and the PKM for their all-around LMG). So why does the US Army use the M249 as a squad auto?
Belt fed makes perfect sense if you can actually park your butt somewhere for a few minutes, mount the gun on a tripod, and link a few cans worth of ammo together. But not if you have to get up and run at a moment's notice.
My best guess is that it's just tradition, an extension of the "horse cannon" concept, in which a team of men can move a tripod-mounted machine gun from place to place on a battlefield. Someone liked that concept so much, they decided to make it so that one guy could lug around a 30 pound LMG with a bipod, and a bunch of other guys in the squad could carry ammo.
I really cannot see any concrete benefit to using a belt fed system, though. You end up with a gun that's bulkier, heavier, more complex, and inherently less reliable. You have to train soldiers a different manual of arms. Because the soldier has to actually lug around the gun and ammo, there's a limit to how much ammo can be in the gun at one time. From what I've heard, in Vietnam the standard M-60 belt length was 50 rounds. Right now, most soldiers prefer the 100 round nylon pouches, since they're much lighter than the 200 round ones.
Sustained rate of fire? The time it takes to reload means there won't be a whole lot of difference there. Pull back operating handle, open cover, remove pouch, attach new pouch, tilt gun to the right, position first round, close cover.
If the cyclic rates of fire between a mag fed and belt fed gun were equal, let's say 10 rounds per second, and it takes 2 seconds to swap a mag, 5 seconds to change belts, that gives an actual maximum rate of fire of 360 rounds per minute for a gun which uses 30 round mags, compared to 400 rounds per minute for a gun that uses 100 round belts. Not a heck of a lot when the belt fed gun weighs twice as much.
Ammo weight, once again there's little difference. 300 rounds in magazines weighs 10.7 pounds. 300 rounds in linked, pouched ammo weighs about 10.0 pounds.
About the only benefit of the M249 in particular is it fires from the open bolt so it cools faster, and has a higher rate of fire. And the weight might help with the recoil (inasmuch as 5.56mm has recoil, even in full auto). But what's the benefit over a magazine-fed M16-based LMG, which fires from an open bolt at a higher cyclic rate, uses larger capacity magazines (maybe decent quality drums), and has some weight added (steel receivers would be a good start)?
It seems like the Russians came to the same conclusion as me, as they saw fit to replace the RPD with the RPK in the squad automatic role (and the PKM for their all-around LMG). So why does the US Army use the M249 as a squad auto?
Belt fed makes perfect sense if you can actually park your butt somewhere for a few minutes, mount the gun on a tripod, and link a few cans worth of ammo together. But not if you have to get up and run at a moment's notice.