Dies from r 5.5x52R (.22 Savage High Power) are readily acquired, but brass is elusive, and .227/.228 bullet availability is patchy. IME, brass is prone to cracking at the neck, even with annealing, so if you do find some, get plenty. Honestly, 100-120 factory cartridges is as good a place to start as any. (I did this with my 5.6x50R Magnum, and am still only on my second box.)