There are two types of posts here. One type appeals to bias and emotion ; the other to logic and deliberation. Yours is of the first type. You can't support your statement with pertinent evidence or logical argument; you rely on emotion and bias. These "children", as you put it, and young adults, are making the same argument that has been advanced by adults for decades now. It is an argument that has fallen on deaf ears despite its innate logic. The argument is essentially that uniform laws restricting the ownership and purchase of certain types of guns or gun modification in conjunction with universal background checks and waiting periods would, over time, reduce the probability of these types of guns and modifications being used to commit crimes, and in particular mass shootings. That's, prima facie, a sound argument, so long as there is reason to believe probability of an instrument being used is related to its abundance and ease of availability.
What these "children" are doing now that is different from past efforts, is to directly confront politicians who persist in ignoring sound arguments in exchange for campaign contributions from the gun lobby. They have made it their goal to see that these politicians who have remained unresponsive to the majority public will shall not be re-elected . I think they will succeed, and I applaud them for taking an effective and practical approach to the severe problem of gun violence in the United States.
Those who continue to harp on Second Amendment rights have not read D.C. v Heller, or if they have, they are dumb to its most germane opinion* which begins on page 58 of the Scalia text. The Second amendment does not grant the right to own and bear any firearm of one's choosing. That was made clear by Heller and a long history of restricting access to certain types of firearms. These "children" are going to succeed where adults have failed!
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*Heller's personal victory here, viz., that the District of Columbia's gun laws were too restrictive in that they effectively denied Heller any access at all to a readily operable firearm in is home and thus constituted a violation of his second amendment right, is of secondary importance. What is most germane here is the Court's reaffirmation in Heller that the government my impose restrictions on the types of firearms that may be owned.