IMR 4320 temperature stability

Reading my notes from this years range book I noticed a 1/2 mill rise on my 22-250 POI when the ambient temperature was over 80 deg F. Groups from 25 deg F to 75 deg F remained constant on POI.

I did a fair amount of internet searches and I can not find good stability data on this powder. Does anyone else have a problem with this powder, or do I need to look further into another cause.

Most of the old IMR powder was not real temp stable. Good powder non the less just watch the high temps. Anymore I just use temp stable powders.