I can pick up a new VXlll 6.5x20x40 at a blow out price. I would be mounting it on a long range big game rifle after being sent to Leupold for M1's. At dawn or dusk I was really curious if x50 can make a difference at 500 plus yards for evening or early morning shots over x40? And at higher X's does the x50 make a difference? Appreciate the feed back.