Utterly Mad

The magwell is actually intended to be the forward grip, since the weapon doesn't require magazines due to FUSION POWER!
The small area just in front of the stock is the small, incredibly unstable, Fusion Reactor in the weapon, the small piece sticking out from it is a safety override that allows the Fusion Reactor to intentionally overloaded, letting it be used as a last ditch suicide grenade, or a regular grenade if you throw it far enough, but it's heavy as fuck.