reasonablenut

That's a ghost-ring rear sight. They're supposed to be very fast for near-range sighting. This is similar to WWII Enfield sights, and they do work pretty damned well.

As to #7 shot, were they high-base loads, or low-base target loads?

1.5 oz of #7 turkey load at 20' might not be immediately lethal, but it will make bleeding hamburger where it hits.

Still, I prefer #4 buckshot, myself.
 

#7 shot is going to tear up anyone within the range an indoor gun will be used, belive me, at 10 feet, there's no significant difference in the wounding of 00 buckshot, and #7 birdshot on flesh.

Behind a barrier, yes, but flesh, no.

THe sling is a hazard indoors, it can snag, or be grabbed by an assailant. Fine for carrying it around in the field. But a pita indoors.

The ghostring site is nice, although again, at indoor ranges, is not really needed. But when you take the shotgun out for fun and games in the sun, it's a great addition.

As an aside, do note that the spread of shot at short (< 10yard) ranges isn't excactly huge. Expect to see something on the order of 1"/yard.
Visiting a range and shooting a few pattern targets will verify this.