That there is absolute bullshit. Stricter gun regulation is irrelevant to gun crimes. Criminals will always have access to firearms and a legitimate gun owner won't go through all the paperwork just to do something stupid.
How many teen school shootings have there been in American? 100's
How many of them have been in England? 0.
Can you not work out that more people who have an opportunity to get guns EASILY means there will be more gun crime.