Question for you, folks.
I have my .22 wmr zeroed at about 75 yds, and was using 40 gr. ammo at the time, as well as ever since. The other day I was in my RFD asking for wmr ammo, and he handed me a box of 30 gr. Curious to try something different, I shot a group of 5 earlier today and was surprised to see it grouping about 1" low, the opposite of what I would have expected (i.e. that lighter ammo would drop less and therefore group high, if anything). The group was also slightly to the right, but there was a slight crosswind blowing that way.
Now, admittedly it was only 5 shots, so maybe not enough to go on, and I was shooting without any sticks/bipod or anything, from a sitting position, with legs splayed and elbows resting on my thighs, so my aim probably wasn't optimal, but all 5 holes were in the same 1" group to the lower right. Is there any general rule about shifting elevation when switching to lighter grained bullets, and vice versa?