.303 wildcat derivatives date from before WWII for a number of reasons, relating to import restrictions, need for suitable meat and skin calibers more powerful than Lever action calibers, state prohibitions, etc.
Factory production began in the 1950s, with wartime machinery bought from discontinued gov’t factories
Super Cartridge Co. ( ex old MF plant Melbourne)
Riverbrand ( ex Hendon South Aust. MH AND MJ plants)
Both makers started by reloading and reforming spent military berdan brass with RWS .250" primers; Riverbrand also had new cases (berdan) supplied by Footscray MG now MF ) with RBA stamp. Powder was war surplus IMR 4740, a Dupont powder made in Australia during WWII. About halfway between 3031 and 4895. We cried when it ran out.
ICI-ANZ , a subsidiary of ICI Britain supplied ammo made with Boxer primers from the 1960s till the early 80s. Inthe 1980s, all three makers had closed down for various reasons ( financial and age of owners for Super and RBA, Company re-organisation and leaving the ammo industry for ICI )
Calibres variously supplied on the .303 case were
.303 soft point ; .303/270; .303/25 severalcase lenghts;
.303/243; .303/22—3 case lengths and a rimless version as well.
There is a .303/ 7mm for converted M93/95 Boer Mausers’ a 7.7x54R (for NSW .303 prohibited) ; a .303/350 aka “Territorian” for Northern Territory Water Buffalo and Crocodile hunters.
Bertram only started making .303/25 cases in the late 1990s.
All these calibers are effectively obsolete now ( no one makes factory made and loaded ammo, although there are some custom loaders who assemble using US OR PRVI BRASS )
AVB TechServices supplies ALL The .303 derivatives
made from (now) Hornady/Prvi/Starline supplied new Boxer brass, either from inventory for the commoner sizes…270, .25, .243, .22 and 7.7x54R. All the others are on a make to order after checking chamber details from customer…not all .303 derivatives are equal.
Allformed cases are trimmed where necessary and neck and shoulder annealed…with flame mark left ( not polished off).
All forming is done sequentially so as not to damage the brass. The sloppy tolerances of chamber neck dimensions require no neck reaming of cases…original derivatives were straight formed from military ca okses, so resulted in thick necks…esp.the 22’s.