I'm not sure about Nickel barrels but I do know after owning both a stainless one and a blued one I much prefer the stainless. Just less to worry about.

That being said I shoot 295 Grain Powerbelt Hollow Points with 100 grains of Pyrodex in the pellet form and it kicks a lot and I mean a lot less than my 12 gauge with buckshot in it. I'm not sure compared to bird shot.
I will say I shot it back to back with my Browning BAR 30-06 which isn't supposed to be bad recoil wise for a 30-06 and the muzzle loader was a lot easier on the shoulder however it also had a rubber butt pad and the BAR didn't.

I don't think you need to go over 100 grains of powder for 100 yards or less shots. 80-90 would probably be fine. I shot a deer last year at around 136 or so yards with the same setup I mentioned earlier and it didn't make it more than 15-20 yards.