My 1st centerfire rifle was a SMLE with a cannister of 400 cordite rounds tossed in for $40.
It was the same rig my grandfather carried at Gallipoli in the all by 3 survivors, 18th Battalion 100 years ago.
The .303 has an astonishing record.
I am in awe of your grandfather and that unit. That battle isn't much known in the states, but it should be. It ranks as one of the fiercest in history.