|What's Wrong with this Picture?|
Last time I looked that component that is circled is a sling point.
You can see an "Evil Bayonet Lug"!
You can legally buy Grenade Launchers, even the standard 40mm. I want one.
You can get a wide variety of ammo for them. Everything from flares to explosive rounds (avalanche makers), to tear gas, to sandbag thumper less than lethal rounds.
I have also see adapters for Rifle, Handgun and Shotgun rounds. Be careful though if you get one. It makes the device a Short Barrel Shotgun (SBS/AOW).
--Don't try to explain to the media. They would F it up.