Most reasonable C&C bullets will completely pass thru an elks rib cage like a 6.5 140gr , 270 140gr etc. This is a soft spot shot. In my experience a tougher bullet is needed when angled shots from front or rear are encountered. This is where you will hit bone & dense muscle & considerably more resistance. My preference for the last 25 years has been the copper mono's. Next to that would be the Nosler partition. Penetration thru the tough parts of an elk is what should determine the type of bullet used.
