For a period when I carried the Queen's shilling, the Oz Army was stoney broke, and on occaision, we had to make do with second grade gear i.e 7.62 Brens and the L1A2 which we called the AR.

The benefit of this (in hindsight) was we got to play with gear that had come out of stores and was invariably in better condition and more reliable than the stuff in our unit armoury.

To cut a long story short, the 30rnd mags would interchange readily between rifles and LMGs without fault.