I got out my John "Pondoro" Taylor book. He gives the .450NE as giving a 480 grain bullet 2150 Fps with a pressure of 17 tons for a ME of 4930 foot lbs & his "knock-out value of 66.3.
He gives the .470NE as giving a 500 grain bullet 2125 FPS with 14 tons pressure & ME of 5,030 Ft lbs & knockout value of 71.3.
From a practical standpoint for use there is little to chose between the two. He does advise when purchasing a rifle to be certain that ammunition will be readily available for it. On this basis I suspect the .470 is the better choice as well as it operates at lower pressure, as I understand it a factor not to be ignored for use in the hot climates of Africa, although 17 tons is not considered excessive for that use. Taylor becomes concerned when the pressure rises to around 20 tons, especially with the British Cordite powder with which most of these cartridges were originally loaded. Apparently it was rather sensitive to high temps.
