The magento sounds good but I work up loads and chrony at the same time so that puts it out for me.
I do the same thing and use a Magneto. Many say they get about a one inch POI shift. I have noticed it on about 50% of my chronographed loads. My 270 WSM was one I saw no POI shift at all. What I do now though is ladder test with it and then when I narrow it down for groups, I do not use the magneto speed.
