I say the Europeans are not going to allow you to "experiment" with their safety. Nor should they.
Experimenting is the scientific way to find the truth, comparing apples to oranges is not scientific very much. If experimentation is not possible , then science can be done by close observation.
More guns means more people get shot, if all other factors remain the same. But factors rarely remain the same.
Actually no, there is just no reason to reach this conclusion with the facts available.
The custom of murdering for infidelity has diminished greatly. Many fewer women are virgins when they marry, and people are getting married at a more mature age.
The decline in murders is also due to the aging of the population. Most murders are committed by younger men between 17 and 29, and there are fewer of them in the population. The percentage of young men in prison has also increased greatly. Percentage wise, not even the South Africans nor the Chinese nor even the North Koreans have so large a percentage of young men behind bars.
Do you think that locking up this huge portion of our population is a useful good idea?
When we stop incarcerating so many, so long, and start releasing large numbers of these guys I would expect another boom in gun sales, even though the first to be released are going to be non violent offenders.
If the people let loose behave well, perhaps the violent crime rates won't rise because of them, proving that we didn't need to lock them up quite so eagerly.