Agreed, have you ever fired an M-249 with an M-16 magazine stuck in the side? Jams constantly. It was better belt-fed, but not much. And, who want a machinegun that fires 5.56mm?
Apparently the soft "assault packs" for the 249 aren't much better. Lots of complaints about them in the Army "lessons learned" report from Iraq.
As for the 5.56mm, well, it's a *light* machinegun. In all senses of the word. Doesn't make sense to me, but someone must want them.
Meanwhile, I think I'll listen to the Marines, who figured it out first and went to the M240G and pitched the M249s into the nearest smelter.
Me!