Yes Daryl,
sounds like they had a cracking day at the range, firing 50+ rounds from this rifle plus others as well in two hours. That puts the rate about one shot every two minutes. Considering time lost to target-check ceasefires, I'll bet some strings were fired a lot faster than that.

Australia can have hot summer days, too, and rapid fire could make things interesting.
With whole magazine loads fired in succession, I'm not surprised it was the boys from the bottom of the stack that lost their caps.