Pic rail/rear sight issues

[Dreamsinger]

I have a PSA PA10 flat top with an A2 "F" FSB. Even with an extended front sight cranked all the way up and the rear UTG A2 detachable rear cranked all the way down I'm off.  I want to keep the A2 front, don't want a full length Pic rail for flip ups, A quad rail up front didn't cure the problem and I haven't found a rear sight with less than 1.41" between the peep cl and the base. The only thing I can think of is that there is no milspec for AR10 Pic rail height above bore cl and that it varies. It must since DPMS manages to make a "Classic" AR10 with a functional A2 sight system. I can't be the only one who's run across this problem. Any cures short of milling the aft 3" down and screwing a section of rail in at a lower depth?

[98Z5V]

Only thing I can think of - it's the extra 0.050" in receiver height that's getting you.

Mine measures .198"  (It's a PSA, not a DPMS).