Copper Bullet member
It is marked .38 Special.The FTR\MA 55 marking indicates that it went through the Factory Thorough Repair process in 1955, at the Lithgow Small Arms Factory near Sydney in Australia. Most of the Australian issue S&Ws were refurbished at around the time of the Korean war. There is some debate about whether the A^F marking denotes 'Air Force' or 'Australian Forces'.
The piece is unusual in that it has a 4" barrel whereas most of the S&W revolvers supplied to the British Comonwealth via lend lease during WW2 had 5" barrels, and were chambered for the .380 Mk.II cartridge, with the barrel marked .38 S&W Cartridge.
Is the calibre marked on your barrel 38 Special or 38 S&W ?
View attachment 783484
Here is a view of one that was FTRd in 1953. It has a 5" barrel and is marked 38 S&W.