You are talking about countries that started off with little to no individual gun ownership, and with less diversity and variety of culture than the US.
The FBI statistics show that the violent crime rate and the murder rate has been dropping for over 20 years. The expiration of the previous assault weapons ban did not cause the rate to rise, nor did its implementation have a measurable impact. You can look up these numbers, they are public.
Funding these studies would take tax dollars from other programs, or would increase the deficit, with no guarantee of ROI. These projects are not clearly in the scope of the government's role in individual lives. There are many private think tanks and universities that would be better suited to enter this arena, and let the government focus on more pressing matters that would affect the majority of Americans lives.