EddieSouthgate: Indeed Remington made/makes 22 Hornet brass - one of my 22 Hornets uses it.
In fact, from a recommendation by a fellow CampFirer hereon (about 20 years ago now), a very troublesome (but VERY beautiful!) Ruger #1-B in 22 Hornet perked WAY up in the accuracy department when I gave up on everything else and switched to nickel plated brass in that 22 Hornet.
Only thing I can think of is the nickel plated brass had a more consistent "neck tension", or something, over the regular brass - I do know the Rifle went from POOR accuracy to very acceptable accuracy when I changed.
I do not recall seeing it (nickel plated 22 Hornet brass) on the shelves of recent though.
Good luck to the O/P.
Hold into the wind
VarmintGuy