Re: best powder for .308win
I have both the 3.5-15 and 5.5-22 on .308's and have used the 32x. I would not go above 22, you lose too much brightness, your wiggles as well as heat waves (mirage and barrel heat) are magnified and your field of view is reduced so much that you can lose time acquiring the target. Plus I believe that the 5.5-22x56 is the strongest NXS made so why not use the toughest.
The 5.5-22 with the NRP2 is an amazing scope, I almost never take mine off 22. There are a lot of guys here who use it, believe Brent and Len are two happy customers of NXS.