I have used various 300 or 350 grainers on bears, moose, (whales), etc out of the 45-70. One of my favorites is the 300 Speer Uni-Cor - which might be similar to the Federal load perhaps. If that load shoots well for you and gives you confidence in placement, use it. A bonded 300 will work as well as either 350 Hornady (or 350 Speer), and if you happen to run into bigger bone chunks, the bonded 300s will be even better.
