"Africa's Most Dangerous" by Kevin Robertson page 117: " The current popularity of lever action guide rifles in the US has kindled an interest in the 45-70 being used on the big, dangerous stuff. Despite some pretty impressive claims of full body length penetration on bull buffalo, this load (Garret +P Hammerhead)still falls a long way short of the legal ME requirements for dangerous game (4,00 ft-lbs of ME). And so the use of the 45-70 on buffalo in all African countries should be regarded as illegal."
I believe Scovill has a video for sale at Wolfe Pub. showing him ventilating a buffalo with an 1886 Winchester. Watch it and you might agree with Robertson's opinion.