Barsness wrote about this, he basically said if you are seeing parallax shift on your target, on a non adjustable scope...move your eye to the rear past normal eye relief, until the image shrinks with a big black donut around the periphery, and your parallax will be reduced or eliminated. It certainly works for me. You plan on shooting "regularly" at 400 or 500...which, on most adjustable scopes I've seen, those ranges are in the 'infinity' range. An example of one is not much, but I sent a fixed parallax low price Bushnell 3200 and some money in to have them adjust parallax to 50 meters, it came back worse than it was originally. And, owning several mid market scopes with parallax adjustments, sitting on the same bench eyeing the target at the same distance, seldom do any of them match the yardages printed on the adjustment ring...I have often wondered if the diopter/focus adjustment affects the parallax settings. I have done a lot of reading on optics and the mathematical rules that dictate their limitations...and understand nothing.
