ARES Defense walked us through their ARES-16 family of small arms. It is 5.56mm and incorporates a Gas-Piston, Short Stroke Tappet operating system. Actually, to configure the various weapons, the ARES-16 relies on different upper and lower receivers. These combinations allow the user to configure the weapon as:
-Sub-Carbine
-Carbine
-Assault Rifle
-Designated Marksman Rifle
-Magazine-Fed Assault Machine Gun
-Belt-Fed Assault Machine Gun
-Dual-Feed Assault Machine Gun
-Belt-Fed Mounted Light Machine Gun
For me, the most interesting configuration was the Dual-Feed (AMG-3). It allows the weapon to be fed by a SAW drum or a magazine. Notice in the photo below that the soft ammo pack sits lower than on the dedicated Belt-Fed gun (AMG-2). Interestingly, the machine gun configurations utilize an upper with non-reciprocating left side charging handle that lies along the top left edge of the upper. You can also see that this upper has a feed tray cover like a traditional belt-fed design.
Available as full weapons or upgrade kits for existing M16/M4 weapons.