We've established that there are a range of factors that contribute to any person carrying out these acts. The accessibility to certain types of weapons is one of these factors.
Again just relax on the easy target. If there were no guns tomorrow it won't make a difference to these radicals. Just change to the next means to kill people. Banning the method is avoiding the issue. You can't ban every method of causing terror.
And I've already said I believe the states should have some increased restrictions and checks on buying guns but it's not going to solve this issue.