Couple of days ago I zeroed my new Optimate Opti-TT 5-20x50 at 50m with 0.22 Eley Subs. Found that using strelok i could get spot on by dialling in or using the mildot reticle at 80m. Then i went shooting bunnies with most at 75 - 85m. Aimed high using the mildots exactly like when zeroing but the round went high. So did the next. Ended up aiming straight at the bunnies and went home with 14. Anyway, today i re zeroed at 50m. The rifle was firing high and slightly right. Sorted that. Checked that i could hit a2p piece at 75 and 80m, using Strelok - fine. Went shooting at the same place for bunnies again and exactly the same thing has happened. The rounds went high and right. Again i ended up aiming directly at the rabbits even though i was shooting to 82m and zeroed at 50m.
Anyone any idea why a scope zeroed at 50m seems to alter to being zeroed at 80m? Not had this happen before, the usual drifts of zero with time but not the same thing happening on successive outings. Not me i am sure. Can a scopes do this sort of thing?