fitted to the Mark I carriage was the standard gun during the war. They were built in Australia and Canada but mostly in UK. Deliveries (from UK production) started at the beginning of 1940 and first entered service with a Canadian regiment stationed in UK during May 1940. No Ordnance 25-pr Mk 2 on Carriage 25-pr Mark 1 were lost in France. This gun fired all charges, 1 – 3 and Super. In 1942, a muzzle brake was fitted to the gun to eliminate the instability caused when firing the 20 lb AP shell with Charge Super at direct fire low elevation angles. To preserve the gun's balance on the trunnions, a counterbalance weight was also fitted, just in front of the breech ring. The designation of the modified gun was not changed. Eventually, all guns serving in Europe were so converted. The Mark II ordnance had six main marks of the barrel: Mark I barrel Original variant with a loose liner. Mark II barrel The standard design, also made in Canada as C Mk II barrel. Mark II/I In 1946, a programme was introduced to modify the gun's breech ring by morticing the rear corners. A corresponding modification was made to the rear corners of the breech block. This was to reduce the instances of cracking the ring. Mark III barrel The Mark III barrel was a Mark II with a modified receiver to prevent the rounds from slipping back out when loading at high angles. It was introduced in January 1944. Mark III/I This was a Mk III gun with the same modification to the ring and block as for the Mk II/I. Mark IV barrel The Mark IV was identical to the Mark III/I, and featured the modified ring and a paired block from new. Mark VI barrel The final alteration of the breech ring made in 1964. Short, Mark I The 25-pounder Short Mark I, or Baby 25-pr, was an Australian pack gun version of the 25-pounder, first produced in 1943. This was a shortened version of the standard 25-pounder, mounted on the Carriage 25-pr Light, Mark 1. Weighing , it was around lighter than the 25-pounder Mark II. The "Baby" was intended for jungle warfare and was only used by Australian units in the South West Pacific theatre. The gun could be towed by a jeep or broken down into 13 sections and transported by