No complaint with the FAL, but my suggestion would be to stick with a tube fed shotgun. That's what our military uses and they train to be reloading while you are shooting, when you can. That way your firearm never runs dry. That tube fed gun is more maneuverable and quicker on target.
You may want to look again. Check out the M26 MASS, which is replacing the Mossberg 500s in US Army service. https://en.m.wikipedia.org/wiki/M26_Modular_Accessory_Shotgun_System
It fires off Saiga 12 detachable mags.
The US military is moving away from pump guns and starting to move to detachable-mag-fed shotguns. One issue is that there hasn been a lot of reliable box mag shotgun designs made and none were successful
In the US until recently - the popularity of the Saiga 12 combined with
The beginning of US production of licensed Saiga 12s and US made clones (Origin 12, etc) has reportedly started to draw US military interest.
I would also point out that several foreign militaries use the Saiga 12 in various configurations. The Russians have been using the Saiga 12 and its cousin the VEPR 12 extensively in Syria by all reports, and are very pleased with it. Seventeen NATO countries have adopted the VEPR 12
in varying capacities.