What's going on here?

[AlanF]

I went to the range today and fired off 12 rounds left over from Lang Lang. There is definitely something weird going on. I left the scope settings as they were from Lang Lang and shot at the same distance (500yd), using a chrono. The vertical adjustment settled about 1.75MOA less than at Lang Lang i.e. it was shooting higher by that amount! Vertical was quite bad, in the same direction as velocity, but much more than the velocity variation should cause. That makes me think its a tuning problem and its currently at a very unstable place between nodes. This could have happened as the barrel sped up over the first 200 rounds. So next week I'll do a ladder test which may produce a very interesting graph. Watch this space.