Gibbs – You rightly state that there was a plethora of conversions developed in Australia based on the .303 British case.

Wildcating in Australia was pioneered in 1934 when Bill Harrison first necked down the .303 British case to .22; paving the way for a whole horde of cartridges bearing the name .303/.22.

Post WW2, every gunsmith had his own version of the round, each with different neck length, shoulder angle and body taper, and every conceivable rifle action was chambered for them. Many of these it seems, were based on pulling bullets from ex military rounds, resizing and reseating a new projectile with the original Cordite charge intact.

Harrison soon abandoned the idea of the full length case because of pressure problems and went on to develop his .303 Crandall Varmint R2 and finally his .22 Wasp.

The problem of developing the full-length case to the inherently weak SMLE action was tackled by Jack Black, who removed the cordite, necked down the case in two stages and re-inserted 28 sticks of cordite, then seating a 45 grain Hornet bullet, resulting in a MV of 3300fps – sufficient to kill roos out to 200 yards.

There were parallel developments in other bore sizes – too many to mention here; but some made it past wildcat status and were loaded commercially by companies such as Riverbrand and Super Cartridge Co.

Some that I am aware of are; .303/22, .303/25, .303/270, 22 Sprinter,

Other wildcats included .22/303 Falcon, .22/303, .243/303, .228/303, 35/303 Pumpkin Roller, and many more.

I’m sure you can add to this list??