The 338 and 45-70 will certainly work for deer. However it is not the big bullet or the velocity or anything but shot placement that insures a quick clean kill. I have never had a deer so much as take a step after being hit with my 257 Roberts with 100 grain bullets. It does not have the bullet weight or oversized bullet to do the work. However when shot placement is perfect or near to it then its the best deer rifle I could hope to have. The same goes for the 6.5x55 mauser that I have taken the most big game with. I pick my shots, no body says I have to shoot a critter with an iffy shot. Take a deer an elk a moose or any other critter you like. Many calibers from 25-06 on up will drop them in there tracks with good shot placement. I have never shot a deer with a 338 but I can second your choice of the 45-70.