The average hunting rifle will "tune" to a particular bullet weight, meaning that you will get sightly better accuracy from that weight. If finding the accuracy potential is a consideration for you, then you play around with different weights.
Each rifle is unique, so someone elses pet load may not suit your rifle. For a given calibre and bullet weight, there are usually one or two powders that have the correct burn rate, and give the best performance - eg H4340 and H4831 for the 270.
Pick up a reloading manual, read it over and over - they have a bunch of recipes. Or you can check the Hodgdon website to give you an idea of the various recipes. If you can find a buddy that has a 270, then you can "double up" - it saves time and money.