...A number 4 birdshot, shot from 3 yards is not accepted as being able to stop a human....
Says who? and you probably need to define 'stop'!! Also...define 'human'....It would probably stop a toddler....but have less of an effect on a 25 stone crackhead off his head.
It's all in the definition R44-Pilot
I'd certainly be stopping if I got a No.4 to the chest from 3yds!! Then again....I'm a lover not a fighter