I posted a while back about which caliber for a big, slow bullet and ended up getting the 22" 45-70. I got a Lee 500gr mold and tried my hand at casting too. I am using 9 grains of IMR Trail Boss right now. I loaded 25 rounds, but only shot one group of 4 rounds. I used my 4 heaviest bullets for this group. They were all within a grain of each other and right at 485 grains. I chronographed these also.
1st shot - 781.2 fps
2nd - 781.3
3rd - 778.7
4th - 769
Don't know what happened with that 4th shot

Anyway I was using the stock iron sights. I haven't shot iron sights on a rifle in a long time. Set a BIG box up at 125 yards and the 4 shot group measured exactly 3".
I need to put a scope on it to see what it can do, then take it off. I kind of like it with iron sights. I would really like to get a peep sight that could be mounted on the scope rail holes. Does anyone know of one?
Recoil wasn't bad at all. I'd say slightly more than a .243 but less than a .308.
Here is a picture of the bullet and a case

