NO, NO, you read me wrong.
A WFN will wound larger at the same velocity, and strike at the same point relitive to your sights. Get a WFN and keep the velocity where it is.
What I was trying to get across is that if this is your only large animal with this gun, what I perceive to be a spine shot may have perhaps convinced you of more killing power than you actually have. If you didn't hit the spine, or if you've killed several deer with various hits using this combo, I'm guessing wrong, but in my experiance, a Kieth 44 bullet will not kill quick which chest shots if velocity at impact is below about 1200 fps, and doesn't develope the impression of lightening till about 1550 fps.