After a few shots it seems I have to re-sight in. Last night I was dead on out to 40. Then today I was low at 20 so i had to adjust the V-zone.. Then I was dead on again. Then later on I shot some more and was dead on at 40 then all of a sudden i started shooting high... Had to re-sight again.. Now I'm dead on again..

I'm pretty sure my scope is tighten down. But maybe not enough???

Any ideas?