Daryl,
I sure won't use a 303 for them, if I ever get the draw for one I'll get something that hits really hard for sure. I think the Snider would even do okay, even with the foot pounds a bit low, but a quick follow up shot cannot be done with those old things. The rolling block would be quicker and hit harder than my Sniders.

A buddy of mine had to kill a Bison last year on a farm in SK, all they had was a Lee-Enfield, took a lot of shots. I would have done it different but was not there.

I do like old technology, but I should really get a Ruger#1 Tropical and be done with it. But the 50-90 seems like it would be a lot of fun too.