Irold
The XTP was one of the original controled expansion handgun bullets, and is never a bad choice. When I am using a jacketed bullet in a handgun for big game, the XTP is my go to bullet. Realize that expansion limits bullet penetration. Thats one of the reasons a hard cast bullet penetrates so well, it trades expansion for penetration. On really big game, I believe a bullet with a sharp cutting profile and deep penetration is warrented. On a whitetail, and expanding bullet works just fine, as long as you stay away from something like a 180 HP at ultra high velocity. That 250grn XTP at about 1200fps should be a relative easy shooting load in that heavy Ruger. It will provide a good balance of penetration and expansion in a 150 - 220 lbs animal. I have taken 8 or 10 whitetails with this load, or the similar 44 mag load, with very good results. It will usually offer complete penetration on broadside rib / lung shots, and is sometimes recovered on shoulder shots, with good expansion. If you are worried about penetration, but still want some expansion, you might want to look at the XTP 300grn bullet at the same velocity. The only down side would be a little more recoil. By the way, as others have stated, that 454 Ruger will safely handle any published 45 long colt load.
Larry