[archy]

This thing is supposed to replace a belt fed weapon and they put the magazine well on the bottom?

Yeah, like on the SAW it's replacing in part because the top-fed magazine feature is problematical.

Why would anyone field an AR or SAW with a bottom-mounted magazine...?

[sig226]

Your logic seems to be that since the SAW has problems with the magazine feed, only bottom loading magazines will work. You ignore the Gatling gun and the Sten, as well as the Bofors, and any side fed gun such every single belt fed machine gun ever produced.

A weapon used for suppression fire needs to be able to fire more than 30 rounds before reloading. If not, then you need to change your tactics such that squad members will only advance if they can reach cover before the machine gun empties a 30 round magazine.