Briot Milled Sixpence

[hibernianscribe]

I've just acquired a rather nice Briot second milled issue sixpence on eBay and am currently awaiting its arrival. It is slabbed by PGCS so I have reasonable grounds to believe it's not a copy - indeed it looks "right" in this respect apart from the fact I now notice that the reverse legend is CHISTO AUSPICE REGNO and not CHRISTO. There is no such variation listed by Spink or North so would appreciate comments regarding this. Could this be an unknown variety or maybe a contemporary fake? Obviously PGCS did not think the latter and for a contemporary fake I believe the die detail is too authentic. Before purchasing I, of course, checked the slab reference number which is genuine for a Briot sixpence of this description.