Do Different Lots of Primers Make A Difference? Let's Find Out!

So, last weekend I was doing a quick test to see how close my 2 batches of brass would be. I got different numbers and was concerned. I forgot something! In the middle I ran out of one sleeve of primers and grabbed several from another sleeve! I think that is the main cause.
This led me down a rabbit hole of lot numbers. I learned how the CCI lot numbers are coded. So, I sorted all my primers by the year and month they were produced on. Then I decided to test 3 lots that I have either 2,000 or 3,000 of the same to see what would give the most consistent results.
These were all produced at the end of 2023, but I think the last ones I used were from January and June of 2023. I believe that the different months gave me some larger than typical results. I am seeing after this test that these produced in the same quarter are much, much closer.
I think my best bet is the ones made in December, so that is what I will work with from here on out. At least through the remainder of this barrel and my next one!
Now, the big question. Is the 5-12 fps difference between lot 1 and lot 2 of my brass that I am consistently seeing something to be concerned with?
Should I lower the powder in the faster lot to see if it will match the other? Maybe keep them separate, but still be able to use the same Kestel data. I don't know, please let me know if you have a good idea!
My other big concern. It seems that between last weekend and the weekend before last, my windage shifted! It seems to be a very consistent shift to the left. Nothing appears to be loose. And each group looks to be the exact same movement to the left.
Is this just a change in my loading? Something caused by the new lots of primers? Or maybe using a different rear bag?
I was shooting at dusk/sundown, so maybe I was not as lined up as I thought I was. Just seems odd it would not shift around after getting off the rifle and back down between groups if that was the cause.
Let me know what you think! I gotta figure it out this weekend. Match is weekend after on the 29th!!

Let me know what you think. Remember to double check your load data if you change primer lot numbers! Some things may very well be different!!
Thank you for watching and hanging out for a few. I hope you have a great rest of your day and an awesome weekend!!

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