Again, there’s a reason the LMGs don’t have the underbarrel slot. Grenade launchers and related weapons also use that slot.
So why exactly can’t our assortment of half-insane survivors decide to attach a grenade launcher to their LMGs instead of a bipod or vice versa? I get that they probably don’t use anywhere near the same mountings, but does it really make a nuanced difference? If most LMGs are designed to mount a bipod and the current system includes those in the underbarrel slot why not let someone crazy enough to remove a bipod add a grenade launcher or forward grip instead?
True. While it would look weird in reality, in Cataclysm terms it’s far from the weirdest.
Now if only the M2 could mount a tripod instead…