I have killed 5 elk with my 308 (and 8 deer). First three with 165gr Nosler partitions, and the last two with 168 Barnes TTSX. All elk have fallen within 100 yards, with most not making it more than 20-30 yards. I personally feel caliber is the least important (within legal caliber options), bullet choice is the 2nd most, but being able to shoot an animal accurately is the most important. Get a rifle you shoot well and shoot them in the sweet spot with a good bullet - they will go down. 308 is great, practice with your rifle, and keep shots within 400 yards.