Are the guards going dove hunting? Because shootin' a man with 7 1/2 bird shot is just downright cruel. To him and the surgeon who has to pick 'em all out.
That 7.5 shot. Maybe they ascribe to the idea that they don’t want to shoot through the walls. (Hint - if it won’t go through sheet rock, it won’t go into a bad guy either.)
There was a shooting last year at my son’s college. Thank God the nutcase was an idiot. He killed one student with a shot point blank to the head. Several other kids were shot at a bit of distance, walking to the ambulances with large red rashes. No doubt birdshot.
One student overpowered the shooter while he reloaded.
One uses bird shot for training it is a lot cheaper then buck or slugs and accomplishes a lot of the things you need in training people with a shot gun.
The 7 1/2 shells are likely for familiarization firing for the shotgun.