I've taken several missouri whitetail with a 45 colt. All with 245/255 gr boolits and 1 with a 250 gr nosler.
All were pushed to around 1000 fps by anywhere from 8.5 to 10 gr of unique.
My gun is a new vaquero and I don't push it any harder than that. My experience has not led me to believe I needed to. Where I hunt its brushy and 30 yd shots are on the long side. At longer ranges added velocity may certainly help with placement.
I started with the Lee 255 RF. My most accurate boolit so far. At 950/970 fps penatration is not an issue. I've never shot a deer completely lengthwise but have done some hard raking shots. The only recovered boolit I have I dug out of the ground behind the coyote it went through.
At this velocity it pretty much just cuts a 45 cal hole. Blood trails were skimpy but not very long. I nearly always saw them go down.
Wanting a little bigger exit wound I went to a 452-429 Keith and had a small HP put in one cavity. This definitely gets me a better blood trail if it exits. It tends to not exit on raking shots but the only broadside it didn't was a very large doe and it broke both shoulders and bulged the hide on the far side. No tracking required.
This year I am trying the NOE version 255 RF with a cup HP. Initial testing shows it not to get as big so I'm hoping for good accuracy and penatration with a slightly larger exit hole. Time will tell.
One of the things I like best about the 45 colt and the standard or just above loadings with a heavy RF boolit is its ability to take small game with out meat damage but still able to handle much larger game with considerable authority.
Side note. I have many 45 cal molds including the Lee 300 gr. My gun will not stabilize it at velocities I'm comfortable with.