Sounds like a great idea if it truly works reliably
No doubt about it, the M4 carbine with M855 bullets is not enough, but I think ultimately we need to get a new higher energy cartridge with a more destructive bullet type in a better rifle instead of just issueing shotguns to some of our warriors. It is time this country abrogated compliance with the Hague convention. Perhaps we need to finally adopt the .276 Pedersen from 1932 with a modern 120gr expanding FMJ.
Another option would be replace the ridiculously short M4 barrels with standard 20" barrels with a short barreled pump action shotgun using a short 8ga shell with the same ballistics as a 2 3/4" 12ga. for greater magazine capacity. Most importantly have the trigger mechanism on a vertical grip attached to the pump.
"In a world devoid of semiautomatics, a properly set-up Webley is the ultimate full-size self-defense handgun."