Hi, Yac...
I think that load ( 31 grains Win 296, 300 grain XTP-Mag ) would be VERY effective on deer, as well as just about any other big game in North America. According to my Hornady manual, 31 grains of 296 should push that bullet somewhere between 1550 and 1600 fps. Hornady used Federal 205 primers instead of CCIs, and their test gun was a Freedom Arms with 7.5" barrel. I have never chrono'd that load in my SRH, but being as how the SRH also has a 7.5" barrel...although I honestly don't know what the SRHs twist rate is...the FAs is 1 in 24...I would imagine that it's within at least 50-100 fps of that in the book. Off hand, I am not sure what that works out to in terms of energy, but that is WAY beyond anything a 44 Magnum can do. I would be very confident in that load for deer. I wouldn't feel undergunned using that load for elk, either.