dhom hit it right on the head.

Fire an expanding bullet well above it's designed velocity range and it is likely to come apart on impact.

You need to find the balance between speed/charge, accuracy, and weight. Somewhere within those 3 items is a sweet spot for each gun.

As long as the bullet expands and does not explode, you have a deer killing round in 44mag or 45 colt. A 240gr SWC does not expand at all and it has taken countless thousands of deer.