I have seen minor variations between lots at similar temps loading the same load for the same gun. Certain powders seem to have more of a reputation for it than others. Reloader 22 is one of these, although so far I have been lucky and have not had a problem.
When I really care, however, I run a lot of shells from the same batch and verify my load/drop chart then save the rest of the batch for final sighting in and the hunt. I'll use odds and ends of reloading runs for plinking and banging steel.