Another observation which may help. When the weather was much colder I placed a couple of gun+scope combos on a table just outside and focused them while they were still warm, noted sidewheel, etc. After they dropped down below freezing I first checked the image before touching anything. They were all still in focus near as dammit. Re-focusing gave the switched sidewheel position. So I don't think the tube expansion/contraction was my own particular issue but it is something inside.
I tried this at 50+yds and also at 16yds with a 50' which is basically the same parallax setting.