What are the authors of those studies trying to prove though?
In Australia, mass murderers chain up and burn down nursing homes (or a backpacker hostel).
Not a 'gun death' in sight, though, so no impact on the studies.
A sad/angry young man breaks up with his girlfriend; gets drunk and drives really fast into the biggest tree he knows; not a 'gun suicide' though, not even a 'suicide'.
You think the guys running studies to make Australia look like a success are going to go looking for mass murders and suicides not involving a gun, in their valiant search for objective truth?