Re: A gun is involved in every single mass shooting.
The amount of ammunition used in the invasion of France in 1944 was so huge it caused major logistical problems.
And in Vietnam, one US battalion went on a mission, dropped at dawn by helicopeters, carrying 2000 rounds per man. By noon they were radioing for an emergency resupply because they were running out.
Members of other militaries I have talked to don't think much of US fire discipline.
The reason the US introduced single-shot / 3 shot burst M16s instead of single shot / full automatic was to at least slow down the depletion of ammunition in the field. I seem to recall it was an after issue add on kit.
Most militaries just tell their troops to use full automatic only when necessary because of the circumstances, and if you need it it's this setting here.