I just wanted to comment on what I learned from shooting with iron sights so far.As I said before ,there is a big difference,especially at 100yds, on where the rifle shoots when it is fired off the bench compared to when it is fired offhand.My Ruger lott,with its 23?? inch barrel shoots 4 inches higher than off the bench and my 308 with its 30 inch barrel shoots 10 inches higher than off the bench.The lott also shoots 3 or 4 inches to the right,compared to when it is shot off the bench and the 308 shoots both the same horizontally when it is fired from both positions.Could it be that the muzzle blast and/or recoil from the lott causes the barrel to move to the right while it is fired?

hmmmm........strange findings. I shoot over 3000 rounds a year with 18 different rifles from 280 Rem to 458 Lott in all variances of field shooting positions, never seen these "claimed" discrepencies.
Maybe a little high/low or left/right, but Its me not the gun & it aint 10"

I I hold the rifle on the bench much like I do from a field position, I find little POI change. It may have something to do w/ your bench technique. Sit up as straight as possible, grip the forend, pull the butt in snug, fire away.

I have found a poi difference, however have also found that it is the bench technique that was at fault. With a field rifle if the hold on the fore end it to hard onto the front bag it will cause a higher poi than if it is held firmly( as you would with a field shot) but with a "resting weight" on the bag. Let the rifle slide back on the bag rather than try to hold it down and imobile. Just my experience.

Von Gruff.

Never seem a difference between bench and standing supported or unsupported.

I would say it's something to do with your technique.