One thing worth adding, nickel "Extracts" easier than brass.
I found this out loading some nickle plated 223, with light loads.
Ammo loaded w/ the same projectile and bullet, but only difference was brass vs. nickle. The brass would short stroke and cause feed problems, the nickel extracted cleaner and didn't jam.
It was "starter" loads on two separate strings of incremental power, 5 shots per step (was testing how the cases "grew" in comparison to one another).
100% of the starting load of the brass case 223 failed to eject, 100% of the nickel plated brass ejected fine. It was an obscenely underpowered load, could barely feel the recoil on the AR...