So far as I can tell from the South African Military Archives, the No.4 rifle saw extremely limited active service with the South African Forces during the Second World War and was not generally issued until the 1950s. I base this view on three documents which I recorded and summarise below:
31.07.1945: (Distribution of Rifles No.4/No.1) Units: 119/30,195. Depots: 31,458/21,996
26.06.1947: "Rifle No.1 Mk.III to be retained as the standard weapon of the U.D.F. (Union Defence Force) and issued to the P.F. (Permanent Force) and A.C.F. (Active Citizen Force) Rifles No.4 to be retained and stored by 81 TS Depot"
26.02.1954: "Rifles No.4........ From 1942 until 1943 some 29,000 No.4 Mk.I were received........ between 1947 and 1948 issues were made of these rifles to local units. At the end of 1948 these rifles were returned to store.......... In 1950 we received 85,000 (No.4s) from the War Office........"