Diagnosis unchanged,but prognosis improved.(grin) Tough for me to dope parallax,with the particular rest you cite and everything is the wrong elevation and ergo's there. 6x's more forgiving by design,than 10x's,12x's or 16x's and a Dirt Flop certainly trumps the "rest" attempt.
I don't have any Centerfire Steel set closer than 450yds and shooting the Titanic inside the 190yd line,really ain't my jam...exceptin' perhaps Grock 34 giggles. Have bought/made a bunch of movers/swingers and keep a few in my crummy,along with distantly/dastardly Rimfire Sillywets and a MEAN 1/4" KYL for same. Have done a good job thus far,not shooting any of my Hummers or Whizzums at said steel.
The Long Range Rimfire Game,being more fun than everything else combined.................