What rifle? Are you talking about the L4? Yes, a couple of Brens were converted to .280 but the problems but abandoned when the 7.62 was adopted. The red 7.62MM mark was never declared redundant as such. It just went into disuse by some tacit agreement when the last of the old .303 Mk2's and 3's finally drifted out of service in the mid 70's or so and only 7.62's remained. I seem to recall that the last 303's in military service were those fitted as the ranging gun on the WOMBAT and CONBAT where the 303 bullet pretty well matched the trajectory of the main 120mm gun. plus the fact that it meant that the gun crew had a machine gun to hose down those who were fleeing the tank they'd just sent to valhalla. Cadets used a mixture of the 303 and L4 guns until the 80's until they - sadly - got the LSW