Yes, high power with NRA match rifles is 3 position. But even with service rifles without spirit levels on their front sights like many bolt action match rifles have to keep 'em level, windage zeros for different ranges seldom varied more than 1/2 MOA in all three positions for those shooting the best scores. It takes some good training and practice to hold a rifle pretty consistantly level from shot to shot, but it can be and is done. And spirit leveled front sights have been easily aligned with the rear aperture sights windage arm so the sight moves perfectly horizontal when the sights are leveled; been done since about 1960.
With scopes in competition, they're easy to level quite repeatably from shot to shot. First, twist the front sight's barrel band so it's spirit level matches a level on the rear sights's windage arm. Then clamp the rifle barrel in a vise so the sights are level. Then remove the front and rear sight, moung your scope, loosen the rings and twist it so the horizontal wire's level. Then all the sights for that rifle are set up the same.
I've always used the same windage zero for all ranges from 100 through 1000 yards for the same centerfire cartridge. Whatever spin drift there was, it was too small to be corrected for.
Last edited by Bart B.; November 24, 2012 at 10:40 AM.