Another note, with bullets of that caliber (not sure exactly what it is, but they look pretty big, maybe .45 cal) even if it was bigger it might be uncontrollable.
edit: Also, the magazine (clip) release button in the concept sketch is in a bad place. A right-handed user would have to release his or her grip on the… grip in order to drop the magazine. The release is usually in a place where it can be pressed with the index or middle finger without moving the firing hand at all.
edit 2: Well, that might work if the shooter pressed it with the side of his or her index finger.
edit 3: Is the low ammo LED on both sides? If not, it would be worthless to a right handed shooter. I wouldn’t put that on the side a gun anyway, because an enemy might notice the little glow and know you’re running low on ammo. It would make more sense on the back of the slide. Regardless of where it is, it should have an off switch for night use.