TorkMag has AR magazines in 35 and 50-round capacity!  By using dual springs and a rolling follower TorkMag manages to cram extra rounds into magazines only slightly larger than a normal mag.  The 35-rounder will still fit in most magazine pouches and those extra five rounds can make a difference.

If you needed more ammo would you rather squeeze the trigger once more or reload?  The 50-round magazine is indeed approaching monopod length.  Time will tell if this dual-spring system and polymer body can hold up to the pressure.  Have you tried a TorkMag?  If so let us know in the comment section below.