The Charles Universal Gas Expansion Laws apply whether you are burning temp resistant powder or any powder.
Guy, I Represent that Beanpole remark and I have asthma, after 10 years of illness, I look like one, and I use a .270 universally (except for elk and larger). I also use a 7mm Rem Mag for deer long range. No umbrage taken, I have been called worse!
I use the age old 130 gr Partiton with 55.0 grains of MR 4350 at 3050 fps. This load has worked for me for lots of years. Alway accurate alway fast enough.