Repairing worn-out 60-pounder guns, Ordnance Workshop at Lovie, 22 August 1917. A major concern in 1917 was the wear that artillery pieces were suffering from firing thousands and thousands of rounds. Each round fired wears a tiny amount of the barrel away, and eventually muzzle velocity and accuracy decrease. Accuracy can decrease catastrophically if the wear is uneven. Because shell production had outstripped production of new guns, the wear problem was acute in 1917; by 1918 gun production had caught up. The problem of wear across the BEF's whole stock of artillery was so severe that it affected operational choices, because the BEF could not use large quantities of artillery to take limited objectives in attritional battles.
Source: IWM photo Q2769.