I've had similar problems with rifles. Not sure I have an answer that fits all questions, but have a couple ideas to check.
As mentioned already, loads from differing sources will print to different points of impact. The type of powder used the type of bullet used, the type of arm will all react to each other to shift windage. No idea of how to predict this.
Presuming you are using factory ammunition: If groups are acceptable and fairly round, adjust the sights and stick to the load that works. Don't buy 'anything' and expect it to all work the same. Next season you may have to find another factory load, as factory ammunition may (or may not) change powder, charge levels (to get same velocity) or different types or lots (batches) of bullets - all of which can change the 'balance' of a load. When one finds a load giving good results, buy as much of that 'lot' of ammo as possible.
If using reloaded ammunition, the situation is similar, but one should think of the same sorts of factors as applicable to ones situation and control.
One rifle I can (a .22 long rifle) would change windage strike with range adjustments. Turns out the scope was mounted with the axis of the scope just slightly out of line with the axis of the rifle bore. (They weren't 'looking' the exact same direction.) Just a thought, but if that rings a bell, check it out. If nothing else seems to help, check it out.