When I was still shooting small bore match seriously, both rifle and pistol, I noticed enough difference between lots that I would buy my ammunition by the case and be sure that all the ammunition going too a match was from the same lot to avoid any deviation in poi. I also tested my match guns to determine what ammunition shot the smallest groups and keep a stock for each gun. The variation in the poi between lots is relatively small maybe 1/8 to 1/4 inch at the worst but even when shooting a 50 foot indoor course that is enough to significantly impact scores.