FTEK,
Carl W. Johnson,Jr. wrote a detailed account of tests of this that he had made.
I read it in the American Rifleman.
It concerns cast bullets with Dacron or Kapok fillers,but,to some extent,it will pertain to jacketed bullets.
It was an extensive test,using 4 different rifles and 2 different calibers.
He used 2 different powders and 2 different bullets.
The groups that he got at 60-70 degrees were different then those at 70-80 degrees,and very different then those at 80-90 degrees.
Not only was the POI different,but the group size was different.
After reading this,I took my Springfield Krag to the range in 30-40 degree weather to check out the loads that were chronographed at 75 degrees.
I'm sorry.I forget the reading,but it was signifigant. My next hunting load will be loaded over max,because my regular load is at max. I will mark the ammo for Hunting only.(I've been shooting the same load for twenty years)It's a jacketed bullet load.
Frank