I note this 577/450 brass for sale at the moment on our national auction site with a buy now price of NZ$80 for 10, made from 24 gauge brass but no indication in the auction notes that are copied below as to brand of brass.

"Auction is for 10 pieces of brand new 577-450 brass for the Martini Henry rifle, ready to be primed and loaded.
This brass has been formed from 24 gauge shotgun brass which is reflected on the headstamp.
Should only be used in rifles in good condition and safe chamber tolerances".