Thanks for the post, this is great information.

PLB - you raise a good point. I was amazed at how much my zero had changed between range trips. Early October trip, temp in the mid to upper 80's versus a January trip, temp in the low 60's. Same ammo, second half of the same box in fact, were several inches off. At first I thought my scope had been jostled, but the shots were "zeroed" horizontally, but were off vertically. Later, I thought about the temperature difference but wasn't aware that it would make such a difference in the point of impact.