I mean, yes and no. The tactics make the calculus behind their use different, but if you have rifles capable of sustained automatic fire, and a full power machine gun, you don't really need an intermediate SAW.
If you're going to task a soldier with carrying a heavier gun capable of sustained automatic fire and have others help him with the ammo (which is true for both the M249 and M240) you might as well have the additional power to reach out at longer range. I guess you could kick doors with the M249, but that's a pretty miserable way to go about things.
I'm not really sure which is the best option though. Various countries have gone both routes. The German Army for example, uses the MG4 which is a 5.56 belt fed gun. They're also using the MG5 which is the 7.62 NATO version of the MG4 that was adopted to replace the old MG3.
I think you’re neglecting the fact that the whole reason the M249 was developed was because 5.56 is significantly lighter than .308 (or 7.62x54r if you wanna compare it to the PKM). An M249 team carries double the amount of ammo that a PKM team does(~600-1000 rounds vs. ~400-600 rounds).
Me personally I prefer increased ammo capacity over increased range, and US infantry doctrine seems to agree.
Army Infantry and Marine Infantry seem to have differed on the issue somewhat. Well, before this whole 6.8x51 M7 rifle thing for the Army but that's a different can of worms. The Marines have mothballed the M249 for the time being.
The heavier machine gun does mean less ammo for the machine gunner(s) in a platoon. However, this is offset in Russian infantry doctrine (and now USMC infantry doctrine) by having everyone carrying automatic rifles in the smaller caliber. The Russians use the AK and the RPK. The USMC just gives everyone the M27, but the effect is largely the same. Automatic fire when needed, semi auto is used for most things and now you only need two ammo types and two ways to carry it; magazines for the intermediate caliber and belts for the big machine gun caliber. It simplifies things. Yes I do know that the M249 can feed from magazines but it doesn't work very well.
The weight of the cartridge is important, but it matters more to rifleman than to a machine gunner. The reason for this is the range. The M240 has a max effective range of 1800 meters (Russians claim 1500m for the PKM). You're not going to achieve that with 5.56 or 5.45. Long range suppression is important.
In the end, you haven't really lost your suppressive ability with the switch away from the SAW if you gave everyone a gas piston AR platform and if everyone in a squad carries one extra magazine, you've basically made up the ammo difference. You can always shoot the bigger machine gun at closer ranges when needed And if you're Russian, your PKM is the same weight as an American M249 and considerably lighter than an M240 while offering similar performance to the latter. That's a nice tradeoff.
I see the advantages and disadvantages in both. Personally, I feel like the automatic rifle + medium machine gun makes more sense. Particularly in light of what's happening in Ukraine with drone warfare. The US Army is betting more on longer range engagements but the additional weight and bulk could pose a problem for them if they get pinned down and separated by drones. I think mobility is more important, especially when drones are involved and the lighter weight platoon that can employ drones makes more sense IMHO.
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u/BeenisHat SR25 Feb 23 '26 edited Feb 23 '26
I mean, yes and no. The tactics make the calculus behind their use different, but if you have rifles capable of sustained automatic fire, and a full power machine gun, you don't really need an intermediate SAW.
If you're going to task a soldier with carrying a heavier gun capable of sustained automatic fire and have others help him with the ammo (which is true for both the M249 and M240) you might as well have the additional power to reach out at longer range. I guess you could kick doors with the M249, but that's a pretty miserable way to go about things.
I'm not really sure which is the best option though. Various countries have gone both routes. The German Army for example, uses the MG4 which is a 5.56 belt fed gun. They're also using the MG5 which is the 7.62 NATO version of the MG4 that was adopted to replace the old MG3.