Re: optimum powder
I get to work on a lot of .270's through our accurizing business. I don't like the reloading software as it never takes into account the variations in throat length and bore tolerence variations from rifle to rifle along with differences in brass thickness. Nevertheless, after working on .270's year in, year out, I have found a fairly basic formula.
Using U.S made brass (I prefer Win or Hornady) and 130 to 150 grain bullets:
In long throated .270's which allow for a COAL of 86mm (3.385") or greater (for a 40 thou jump), H4831sc works best.
In short throated rifles with a working COAL of 84mm (3.300"), it is almost impossible to fit enough H4831sc into the case to obtain optimum velocities. In such instances, H4350 gives best results.
For light 90 grain bullets, H4350 will suffice however Varget is also good.
Becasuse many of my clients also use our outfitter services and want to hunt pigs at longer ranges, I usually try to develop a load utilizing a 150 grain bullet at maiximum yet safe velocities. In most instances, due to the trend towards shorter throated factory rifles, 54 to 55 grains of H4350 is the optimum choice, giving 2920fps in 22" barreled rifles and around 2950fps in 24" barreled rifles.
A couple of clients have pushed 150 grain loads as high as 2980 to 3000fps and have been using these loads for many years. This is however, relative to individual barrel tolerances. In contrast, I accurized an A-Bolt which had such a short throat that factory ammo was jammed into the lands during chambering. The A-Bolt suffered sticky extraction with factory ammo and with 150 grain hand loaded bullets, could not be loaded past 2800fps.