I use the exact same load as TomT, Hornady 174 gr RN over 38 grn IMR-4064. I took a 100 pound whitetail doe at a measured 110 yards last year and had no complaints about at all about how it worked.

I'm taking a very similar load 174 gr RN over 39.5 gr 4064 in a .303 British Martini Henry this year. At southern Alabama whitetail ranges (200 yards and under, mostly 100 and under) I don't think there is a noticeable difference between Rn and SP.

Learn from other's mistakes, life is too short to make them all youself.