This target was at 15 yards and we shot it twice.

The spread was about 20 inches.

Then at 20 yards, and the spread was about 22 inches.

You will also note that this is the last target that had all 9 pellets on it.

Then at 30 yards, and only 2 pellets stayed on the target.

Where did those other 7 pellets go?

I better know, as I am responsible for everything I send down range.

Lastly, at 40 yards. I managed to get 3 on the target.

Where are the other 6 pellets?

I better know, as I am responsible for them too.

When might we need to know the "exact" size of our group?

Well, one situation might be if we had a bad guy behind a hostage like this.

We might have to take the shot, and if we knew the yardage and the spread of our load in that particular shotgun, we could take the shot.

But we would have to aim towards the edge of the target to be absolutely sure that we did not put a pellet onto the hostage.