Looking to see if anyone else has ever experienced this...

I zero'ed my new 10 FCP-SR .308 with 168gr Federal SMKBTHP about 2 months ago. This past weekend I went out to a range to get some true muzzle velocity and do a box test with my scope. I had some rounds left from the same box I used to zero with, so I decided to use the up first before I switched to the new boxes. I anticipated a slight POI shift as I zeroed at an indoor range, and now shooting at an outdoor range. There was about a 1/2 to 3/4 in POI shift. That's not the issue though, just giving some back ground. Once I used up that box and was happy with my grouping... I switched to a new box (Different lot). Moved my POA to an fresh area on the target and shot the first round and wouldn't you know it... 2" at 100 yards. I was like WTF!! Shot 2 more rounds with the same results. The group was tight, just 2" higher than my POA.

I've been shooting off and on for the past 30 years. Even dabbled in reloading for a while. I've never had that large of a POI shift when firing the same brand/grain ammo. Certainly didn't expect that from a match grade factory load. Once I dialed down 2" on my scope, the rest of the box grouped as expected (POA equaled POI).

I changed nothing on the rifle or scope between lots. I simply loaded up the new lot and fired.

My only explanation to this is different lot #'s. Anyone else experience this?