edit : lots of replies while I was slowy typing, I thought I'd be the first reply (I'm getting old I guess).
MOA is an angular measure, inches is linear.
Sights on a rifle operate on an angular measure principle, not linear.
Our eye is very close to the sights (front and rear) so a tiny linear (parts of an inch) adjustment at very close distances produces an ever increasing adjustment as the distance increases. If I want to make a 200 inch adjustment to my point of impact I must know the distance the adjustment is desired in order to make the angular sight adjustment. Its a given that I cant adjust the sights (or scope) enough to make a 200 inch change at 25 yards but I can make a 5 inch change at 25 yards, this very same 5 inch change at 25 yards works out to about 200 inches of change at 1000 yards.
It'd be a little cumbersome to preface each sight adjustment with the distance as in the 25 yards vs 1000 yards example, its much easier to say "20 MOA" of adjustment in UP, DOWN, LEFT or RIGHT.
MOA does not need a distance clarification for sight adjustment, its already angular.
Inches needs a Distance component to convert to angular sight adjustments.
A 5" group doesn't sound too good as a simple and non-clarified statement. A .25 MOA group is pretty good and can measure a linear 5".
"Is 5 inches= 5 MOA?
If so why not just drop the MOA thing and say inches?
5" can equal 5 MOA but only at once very specific distance, someplace very near 100 yards distant.
Last edited by Dave King; 01-04-2008 at 05:45 PM.