It's only "many mils high" inside of 50 yards, because it's a consistent linear rate of increase from 0" at 1000 yds to whatever the offset height is at 0 yds.
If the offset height is 4", the laser impact offset will be:
1000: 0", 0 mils
900: 0.4", .012 mils
800: 0.8", .028 mils
700: 1.2"...