I have been loading for the .270 since about 1980. For years my go to load was 59 grains of IMR 4831 lit with a CCI 200 behind a Speer 130-grain Grand Slam. I tucked the bullet up to within about .010" of the lands, and got cloverleafs at 100.
I later swapped to AA 3100 (now discontinued). I was told by the Accurate Arms rep in the mid-90s that this was the same formulation as IMR 4831 but nitrocotton based as opposed to nitrocellulose. Also that it was about one grain slower than the IMR powder, and because of the cotton base, burned cooler.
I made the change with the AA 3100 and now load 60 grains of that powder with all the other variables the same. This load chronographs at 3150 from my 22" BDL, and is a tack driver.
I think I would stay with the IMR formulation since the AA powder is now discontinued. And as with all handloads: start low and work up SLOWLY!
Hope this helps...