Quote Originally Posted by Kiwigrunt View Post
Light MGs like the Minimi (both calibres) obviously attain their reduced weight – and manufacturing cost - by virtue of lighter materials. The compromise is that the gun will rattle to bits a lot faster than a MAG58. That suggests that they should be replaced a lot sooner. Been-counters won't like that, because that would nullify the lower procurement costs.
You're pretty much spot on here. I'd also add, though, that the MAG58 is capable of sustained fire for extended periods. The smaller Light MGs are suited for bursts over extended periods - while you can put a belt through them in a single burst, it tends to drastically reduce the life of said barrel (and rest of the weapon). It really is a compromise. When you're patrolling or assaulting, the LMGs like the 7.62 Minimi are wonderful. It's when you're prone behind the gun firing, though, that you simply can't beat the heavier, solid MAG58.

As to the USMC IAR I've got my own doubts about it. I suspect that it is in many ways a product of the recent wars where 'winning the firefight' was achieved against a lightly armed and elusive enemy. If you're facing an enemy firing interlocking machine guns back at you from dug-in positions, I suspect the weight of fire from a belt-fed machine-gun to regain some form of initiative/suppress the enemy's own rapid firing weapons, especially when you know roughly where they could be firing from but can't identify the exact firing points is worth more than a heavy assault rifle (IAR).

However, despite my above reservations about the IAR I also think that the USMC may have made the right decision albeit for the wrong reasons. With the improved sights we are now getting down to personal weapons, a heavy rifle with magnified optics and the ability to acquire targets through thermal, IR or hybrid views the ability to identify and acquire a target is greatly improved. If you can deliver accurate, repeated fire then the traditional need for bursts to suppress an area is almost removed. I'm pretty much in love with 7.62mm DMWs, you might have noticed