Hi dad:
You really don't need heavy loads for deer, just something to poke a couple of holes in the lungs and it's all over. Having said that, I am using a recipe that is probably more than is needed for deer---------------but where I hunt you never know when you might happen upon a blackie. I am using Hornady 350 gr JFP over 50 gr. of IMR4064. It shoots 4 inches high at 100 yards and 9 inches low at 200 yards.. Its PBR is 175 yards for deer sized animals. And it is accurate.
Lots of choices with a 45-70!!!!!!!!!
Mc