bonanza,
I see no reason why they would not,although I do not have a 50-90,I have shot plenty of copper out of my 45-90& 45-110,I used Speer,Remington & Hornady,from 300 gr to 500 gr.
You will get some copper in the barrel but it comes out easy enough,I am going to shoot some Barnes 450 gr in my new 1885 cal 50-110 soon as the weather improves!