I saw evidence of this load density and temp stability business years ago with IMR4831. It did better in the 270 than the 7 RM once temps got into the 0-10 degree range.

This was in the days before there was an internet so no one to really bounce it all off on. I stored it in memory and moved along.



The 280 Remington is overbore.

The 7 Rem Mag is over bore.