The ammunition is fed from the magazine above, situated so that it’s above the barrel for the best weight distribution. The spent cases are ejected straight down through the lower’s un-used magwell, making it great for lefties.
There’s no gas system, instead the 5.7 upper has a blowback operation with a free-sliding bolt, which is the only moving part.
The upper includes almost three feet of Picatinny rail space and vent holes for cooling during sustained fire.
The free-floating 16-inch barrel includes a proprietary multi-port flash suppressor and comes with a “correct-weight recoil buffer” tuned for 5.7 ammo.
The Gen 2 model has a fluted barrel, saving weight, and an updated charging handle, ambidextrous mag release, and an extended rear accessory rail for the mounting of a wider variety of optics.
So what are the advantages of such a franked-gun? Well, for one thing you can have 50 rounds of light recoiling, speedy 5.7 ammo on board without toting around an awkward and huge box magazine or drum. You hardly even notice the P90 magazine is there.