I'm more than impressed with the 45 caliber 250gn Hornady XTP based on this years hunting season and may consider using it in the 450. Both my father in law and I took full size northern missouri does with this bullet this year, his was a midrange load of 777 (doe taken at 80 yards or so) and my load was a max load of Blackhorn 209 with the xtp (doe at 35 yards quartering). I have yet to chronograph these loads but the max load of bh209 may approach 450 velocities.
Both bullets recovered on offside hide with good mushrooming.
Here is my recovered bullet - weight 238.4gns, .867" max measured diameter.