Since the concept is to replace the magazine of gund and put the rounds in the barrel would you want to use it as a side arm?
It's not able to jam and if you have a dud it is ejected by the bullet behind it. Reloads would be a btich compared to a pre-loaded clip I would imagine. I wouldn't carry around pre-loaded barrels.
I saw the 40mm grenade launcher that can fire 1million rds/min. They said it could take out a battallion of tanks, I wonder is this possible if they are moving?
I think it would make a great cheap replacement for close-in-defense guns but again the reloads, how do they overcome quick reloading without the chain ammo?