FightLite is a Florida company well known for their belt-fed AR upper receiver groups. The AMG-3 boasts a 50% weight reduction over the M249 SAW.
What makes the Assault Machine Gun 3 stand out is the side folding feed tray cover which allows you to mount longer optics to the Picatinny Rail.
Additionally, it operates reliable with both linked ammunition as well as via a standard box magazine. Piston operated, it pushes less gas into the face of the shooter and like all FightLite Belt-Feds,it features a Quick-Change barrel that can be swapped by the user without tools in as little as 3 seconds. AMG-3 barrels are available in 12.5″, 16.25″ and 20″ inch lengths for both heat mitigation and to meet operational needs.
I own one of their MCRs, and the feed cover is its weakest feature but I love everything else about it. If they figured out how to integrate firing from an open bolt it’d pair beautifully with the weight reduction.
The M231 fired from the open bolt, so I doubt it’s a “figuring out” how to make the MCR fire open bolt and more about a desire to do so.
Long ago, the ATF issued rules that any firearm that fires from an open bolt is considered “readily convertible” to a machine gun and since then, no manufacturer has been able to seel open bolt guns to civilians.