Why 45gr? Long distance?

I've shot only one coyote with my Tac20. It was at 125yds
using Hornady's first .204 pill, the 33gr V-max over 24gr
H4198. She just fell over....didn't even kick...not once. The
bullet began fragmenting soon as it got into the lungs,
destroyed the diaphragm, and shredded the frontal lobe of
the liver. Nothing exited. A co-worker has experienced the
same results to 300-350yds with a 20 VarTarg using 32gr pills.