While some have had success with the 77gr tmk on elk, I have no experience with doing so. Based on my own experiences with a respectively much larger cartridge, I would not use or recommend a 5.56 for elk. I have used a 5.56 (60gr nos partition) on deer ribs, and based on that experience, I would not want to use anything smaller. Accuracy and distance willing, I would shoot one in the noggin/neck with the 50gr out of a 5.7. If you do use it on some deer ribs, I would love to see your results/necropsy and possibly change my mind.