Think hard about what you said, especially the highlighted part.
What are the odds of a survivor of a gun related violent event changing his/her mind about guns in general and the Second Amendment in particular? At best, 50/50. In other words, we do not know unless we interview literally every such person and record their responses. But the bottom line is that no one, not even the NRA, can silent any such survivor from speaking out against guns, not just gun related violence. There are plenty of such survivors, from ordinary people like David Hogg to US Congresswoman Gabby Giffords, who dedicated parts of their time against guns. The problem that people outside the US have is that they believe that their opinions about guns are correct and dismiss any counter arguments against theirs. In other words, YOU are less interested in rational discussions than you are for simple criticisms to satisfy your feelings about US. Nothing more.