What caliber?

[Maxxis31]

I've killed just as may elk with a .243 as any other weapon. I would never tell anyone it's too small to hunt elk with, I've seen them kill way too many.
I purchased both my kids 10 & 13 a 6.5 Creedmoor for an all around rifle. Personally I shoot a 280AI when I hunt with a rifle.
I've killed more bulls and bucks with a bow than a gun so I feel like any rifle is more than adequate.

 

[KurtB]

Daughter killed her bull at 350 give or take with a 30-06, 18" barrel and 155 scenar at 2775 FPS. Worked well.

Watched son dump a young bull at 400 yards this am. 6.5x47 lapua, 18" barrel, 140 Berger vld at 2670 FPS.

Seemed to work just fine in both cases.

 

[antelopedundee]

I've heard it said that the ol thutty thutty has killed a trainload of deer ANDDDDD wounded about as many.

 

[carl1775]

It's not the round, it's the shot. A .177 pellet, can kill an elk. While I don't condone attempting to harvest that large of a bodied animal with a pellet rifle.... It comes down to confidence, proficiency and terminal performance. All three work together. The better you achieve one facet, the less efficient you need to be in the other two. That said, Just because you shoot a .50 BMG, doesn't make your shot an instant kill. I believe that individual State natural resource offices set pretty realistic limits on minimum weapon requirements.