Oh hey, bit of useless info here, but what the heck.
Found out yesterday that with the remington slugs I use at 25 yards the slug is a half inch low. At 50 yards 2.1 inches low. At 75 yards 5 inches and at 100 yards 10.4 inches low.
Sight it 3 inches high at 50 yards and aim center mass. Good to go.