It actually works in every country that bans these damned things.
There have been no such attacks in Spain, Portugal, Japan and many other countries.
This has been examined very thouroughly here and elesewhere.
Is there any reason, I mean reason not feeling, to consider this to be a true statement?
I think that people who want the result to show that gun bans have positive results , cherry pick the examples with abandon.
By cherry picking the opposite way I produce Germany in 1936, Mexico right now, China in 1960, etc...
My real point is that my examples and yours together might be something like a fair survey which strictly proves that the results of gun bans are not easily predictable.