I shot a bull the following year with a 140 TSX from a 270 WSM. The bull didn't take a step. The bullet shattered the on shoulder, turned the lungs to ribbons, crushed the off shoulder, and was caught in the hide on the off side. Somehow the Barnes "petals" were sticking out in the air on the off-side, but the body of the bullet was stuck in the exit hole. One petal sheered off somewhere inside, but the bullet stilled weighed 122 grains after cleaning.
Both bullets made the lungs inoperable. I don't know what the "knock down" power was. I know the Barnes was the bigger bullet after doing the job. The Barnes had better penetration for sure.
I agree with Colorado Cowboy in that shot placement is way more important than bullet choice. Find one that shoots well out of your gun and use it.
Just remember that 180 grain CoreLokt is going to be 150 grains or less really soon after impact.