Ward, A few days ago, you said this: [ QUOTE ] Another area of maintaining your zero can be affected by the light and wind. If you zero in full sun-light and then shoot in an overcast condition, (shadow effect) your poi will be ½” low at 100 yards. If the sun is at 9:00, poi will be ¼” right. If it is at 3:00, poi will be ¼” left. [/ QUOTE ] Couldn't explain the light theories (in terms of scope use) to myself in common sense terms but: ...over the last 2 days, with dark overcast alternating with bright sunshine, I have absolutely 100% smacked-in-the-face seen the 1/2 minute up/down taking place. /ubbthreads/images/graemlins/ooo.gif Grateful if you'd have a squint at this thread: http://longrangehunting.com/ubbthreads/s...=true#Post58820 to see what yout take would have been on the situation....... have you any other 'not widely known' zero shift tips (ie other than wind , temp, humidity, pressure)that you'd be willing to share?