I put a 10x42 on a .300 RUM, and the RUM killed it in about 50 shots, groups opened way up. Spent the coin for a Nightforce 3.5-15x50 and the groups shrank back down, instantly, and have stayed there.
I still have a 16x42, which has never been used on anything bigger than a .308, and it still seems to work as far as an aiming device, as long as you ignore the internal objects that sometimes float into view
