[img]http://us.news2.yimg.com/us.yimg.com/p/ap/20011212/capt.1008185373attacks_military_lon124.jpg[/img]
US Marines with the 26th Marines Expeditionary Unit (MEU) India Company Special Operations Capable (soc), train in the hangar of the USS Bataan, Tuesday Dec. 11, 2001, as they prepare for an eventual mission in Afghanistan. The US amphibious ship is sailing off the Pakistan coast as part of Operation Enduring Freedom. (AP Photo/Patrick Baz, Pool)

the newest creation from the makers of "NERF" style assault weapons.Rotating chamber,and low velocity yellow balls make it a operator's nightmare,with little firepower,let alone lack of "threat of force" capabilities,since it makes a "ponk" noise when fired.
In the picture it looks like they just got out of the elevator after returning from the lower levels of the ship,where the queen alien has followed them up,that's why they have that "look" in their face.They are now running to get the larger "belt fed" Nerf gun.BLack of course.

In the GFD they asked the same question, it is a Mk153 SMAW, originally the Israeli B300.  It designed as a bunker buster, the standard round has a dual action fuze, if it hits something hard it goes off, if it something soft it buries itself prior to detonating.  It also has a HE Anti-armor round that is not standard issue

The picture is minus the actual round that attaches to the rear to the launcher.  You can see the 9mm spotter rifle on the side though,