Perhaps the most common question I'm asked when I give elk hunting seminars is the caliber of rifle to use. I don't believe there's only one perfect elk rifle, as some folks do. Most rifles will work fine, just as a Ford or Jaguar will get you to the same destination, but one offers more class and will get you there faster.
Choose a rifle with sufficient energy to push a bullet with adequate velocity, as well as enough foot pounds of energy. The latter is the most important, with a minimum of about 1,500 foot pounds at point of impact. I believe a .270 is the lightest you should consider for elk, and I'd suggest a larger caliber if you are up for it. I shot my first 19 bulls with a .30 - 06, and currently I've been seeing a lot of a 7mm Rem. Mag. The .300 and .338 mags are ideal choices if you can take the rough treatment of the hefty recoil. An elk is a big animal with bones much larger than those of deer. Keep that in mind. You may also expect shots out to 300 yards in elk country. Beyond that range, accuracy gets iffy.
My favorite .30 - 06 bullet is a 165 - grain Federal Trophy Bonded Bear Claw. For those who want a heavier projectile, the 180 - grain is also an effective elk load. The 140 - grain Fail - Safe Supreme made by Winchester works well in the .270, and is a favorite of many elk hunters.
I've been a fan of a bolt action ever since I began reading Jack O'Connor when I was a kid. As with everything else, different actions appeal to different people. My only objection would be against the semi - auto, which is likely to jam at an inopportune time, especially since elk hunting offers snow, sleet, ice and pesky branches and forest debris swishing against and into the action. I don't want any more problems than I already have when I'm elk hunting. I've seen enough semi - autos jam that I'm wary of them, and I don't mind telling you so.
Optics are a must. A dependable scope that is lightweight, offers clear resolution and doesn't fog is mandatory. Though the 3X9 scope is very popular, I've gotten along with a straight four power for most of my adult life. Binoculars should likewise be of a quality brand, and they should be lightweight, easily focused, and waterproof.