The so-called “Wildcats” were factory rounds, made by Three different makers (Riverbrand, of S.A, and Super, of Victoria, and ICIANZ of Victoria)…so, a factory cartridge, even if in a small way compared to a US “Factory” cartridge.
The .303/25 and the .303/22 came in several length variations, the most common being 56mm (original .303 case length) but the .22 variants also had 50mm cases, and 45mm cases (or 43mm)
The .303/25 Rimless was also a “factory” cartridge, with the Packets overstamped “Rimless” after the .303/25.
Names are as follows:
.303/22 Full length “Falcon” .303/22 (50mm) “Sprinter”, 303/22 (45mm)
"Wasp "or “Hornet.”
Initially, in the 1930s, cases were made by simply necking down and annealing ex Military cordite cases…the annealing was required due to the particular means of making Cordite .303, which left the neck and shoulders brittle. Primers for the .250 pocket were supplied by Kynoch and after WW II, RWS (Non corrosive)…Super used RWS primers almost exclusively, and mentioned the fact on the packets.
With the introduction of Boxer primed cases, new brass could be made, with improvement in reloading capacity (Berdan Military cases usually failed after a couple of reloads)
The Rimless versions are connected with a strange conjunction of War souvenirs, Stupid laws, and ammo availability…After WW I, 7mm ammo was not readily available for the hundreds of Boer War Rifles souivenired in 1902…so Gunsmiths went about “convberting” them either to .303/25, or even .303 284 (“7mm”), This also involved converting the Bolt face and the extractor and the magazine lips…an onerous Job ( I have seen one such…a perfectly good collectible ruined with the best intentions) into a .303/25 Rimmed.
By using a “rimless” case, the only thing to change was the barrel…the Mauser Bolt handled the slightly smaller .303 (rimless) head easily.
Similarly, some WW I and WW II German Mauser 98s were converted early on. By the 1960s, the freer availability of American calibres led to the demise of these “special” conversions for Mauser rifles.
The other problems relate to NSW having a ban on “Military Calibres”…so all “Military rifles” had to be in a “Non Military Calibre” hence the .303/25, .303/270 etc. ( 1930s to 1975). Other states werren’t so anal…until 1996, but that’s another story.
Both companies (RBA and Super) produced “Remanufactured” ammo using Aussie Military once-fired (Berdan) cases, even into the 7,62 Nato era ( .303 ands all its “variants” and also .308 and .243 were made from Milsurp cases)
They even had Footscray run a few batches (initially) of New berdan cases for them, before switching over to Boxer cases in their own plants ( or made under contract by CAC (New Zealand) or ICI ( Australia).