I have never heard of any P.H. carrying a 45-70 as his or her backup rifle for dangerous game. I have never heard of, or hunted with any P.H. who suggested that their hunter should bring a 45-70 to hunt dangerous game with. These people spend their lives in the bush, and have a hell of a lot more experience hunting this stuff than me, so I will defer to their expertise on the matter. There's got to be a good reason they neither use, or recommend the 45-70.