This might help
According to a Report on the Artillery of the South African Republic from 12th October, 1899 to 30th May, 1900 by M. Casson, [who was in charge of Begbies and Wrights works at the time when they were manufacturing gun ammunition (translated copy at the Royal Artillery Institute, Woolwich)] projectiles for the Krupp and Creusot guns used by the Boers included (1) cast iron common or ring shell (2) shrapnel shell (3) case shot. The last mentioned was a zinc projectile, with wood base, filled with lead balls (12mm diameter for the 75mm field guns, 15mm for the 155mm Creusot Long Tom compared with average diameter of 12,7mm (0,5in) of British shrapnel used with 12pr and 15pr guns). Photographs exist which appear to show the case shot, and the Museum possesses a complete round. The report states that the 75mm field guns were initially issued with 2 000 rounds per gun, of which 500 were case shot which were never, or rarely used, the case shot being almost always abandoned in the retreats. Case shot were shrapnel-filled and lacked both fuze and bursting charge, being designed to break up either in the bore of the gun, or immediately after discharge. By 1899 it had been rendered virtually obsolete by the increased effectiveness of rifle power, and while the British gun also still carried case shot two rounds on the gun and one or two on the limber Diamond Hill is the only quoted instance of its use. Should extremely short range fire be required, the effect of case shot could be duplicated by using shrapnel shell with the time fuze set at 0, when the shell would burst within 50 yards of the muzzle. Case shot was, however, produced in South Africa for the Boer guns, and the McGregor Museums specimen comprises a zinc projectile, as described in the report, fitted with a Krupp brass cartridge case.
This re-use of cartridge cases was standard practice amongst the Boer forces, owing to shortage of ammunition. Artillerymen operating at the front had express orders not to keep the cases, but to return them to the Gouvernement Artillerie Werken in Johannesburg for cleaning and re-forming. The work was done and shells manufactured (according to the report) at several factories Thomas Begbies foundry (the major source, until the explosion there on 24th April, 1900); ZASM (The Netherlands South African Railway Company) which suffered from having no foundry; the Factory (Village Deep) where most of the fuzes were made; Messrs Wright, Boag & Co., responsible for some of the casting; Delfos Brothers, etc. Pom-pom cartridge cases were also re-used and the section of the report dealing with ammunition for the Maxim-Nordenfeldt reads:
The 1.5 inch guns were fired a great deal at the beginning of the war, so that the great stock at the Artillery Camp, received at the commencement of 1899, was soon exhausted. In February, the Gouvernement Artillerie Werken received an order to make this ammunition. On account of the enormous difficulties experienced, they were not able to make the first projectiles till the end of March. During the month of April, they made about 2 500, of which one third was lost in the explosion. Afterwards, they supplied the Transvaal Government with about 3 500, of which about 1 500 were at the Powder Factory on 27th May and were sent back to Pretoria with a great quantity (about 5 000) of re-formed and re-capped cases; of these 1 500 hardly one quarter was completed; the remainder were not loaded or fixed in the cases.
At the Begbie factory, they left some thousands of projectiles in the yard whose casting had been stopped a fortnight before the closing of the works. The casting was done by the firm of Wright, Boag & Co. . .