AP5 accuracy issues with irons/misaligned sight(s)?

Took my AP5 to the range for the first time today and might have a misaligned rear sight? I was hitting low left consistently by ~2-4" at maybe 15 yards, replicated by a buddy. We maxed out the windage adjustment to get there (dialing adjuster counterclockwise), it was farther low left prior to that. Grouping was tight and I didn't have any malfunctions in 250 rounds, so that's something. Didn't have a tool capable of adjusting elevation unfortunately, so that was what it was.

Am I doing something wrong with the adjustment, or do I need to RMA?