Acy- You don't need high velocity in the 45-70 to kill deer. I don't know what distances you plan to hunt at, but with a 45-70 I know it won't be great. Last year, I took a large doe with one shot from my old Marlin 1895. This was a 325 gr. cast RCBS bullet, at a screaming 1700 FPS. The distance was under 50 yards (about 30 as I recall. Quite simply, I had a 1/2 in. entrance wound. Also a 1/2 in. exit wound. The doe spun around in a circle 2 or 3 times, then ran for the nearest fence, (about 20 yards away). She didn't make it. She made a mighty leap, but didn't clear the fence. Too weak. Too much blood lost. As stated before, a 45-70 is already the diameter of a well expanded 30 caliber bullet. Too many people put too much emphasis on expansion. While it is important with minor calibers, with the 45-70, it's an unnecessary luxury. Complete penetration, is complete penetration. My Marlin stopped the deer faster than my 30-06 used to. At about the same ranges, too. Another point I'd like to make, is that maximum velocities can actually reduce penetration with cast bullets (you'd likely never notice it on deer), but you may also find better accuracy and greater shooter comfort if you don't shoot the train-stoppers for hunting at the moderate ranges the 45-70 is suitable for.