I live in Montana and have hunted those animals for a long time. Any of the 7mms is adequate for antelope and muleys. I've killed more pronghorns and deer (whitetails and muleys) than I can count with a .280 Rem which is a 7mm. Don't worry about them being too powerful. In the west, shooting ranges could be a lot longer than you might be used to and wind plays a big factor - a heavier faster bullet can really help in these situations. But follow Hunting Man's advice and be sure you are shooting at a range that is comfortable for you. No rifle and caliber combination, no matter how powerful, can make you more effective than YOU are as a shooter. Good luck on your western hunt.
Last edited by onehorse; 03-28-2015 at 12:38 PM.