有这原因，更关键的是与宪法有关，美国是法制国家，宪法地第位至高无上，修改宪法是需要过很多很多门槛的。

WORDS FROM THE FOUNDING FATHERS ON THE RIGHT TO KEEP AND BEAR ARMS

"I ask, sir, what is the militia? It is the whole people.... To disarm the people is the best and most effectual way to enslave them.... " --George Mason

"No free man shall ever be debarred the use of arms. " --Thomas Jefferson

"Arms in the hands of citizens may be used at individual discretion . . . in private self-defense. " --John Adams

"The Constitution s hall never be construed to prevent the people of the United States who are peaceable citizens from keeping their own arms. " --Samuel Adams

" . . arms discourage and keep invader and plunderer in awe, and preserve order in the world as well as property. ... Horrid mischief would ensue were [the law-abiding] deprived of the use of them. " --Thomas Paine

"[The Constitution preserves] the advantage of being armed which Americans possess over the people of almost every other nation...[where] the government s are afraid to trust the people with arms." --James Madison

"A militia, when properly formed, are in fact the people themselves...and include all men capable of bearing arms...To preserve liberty it is essential that the whole body of the people always possess arms and be taught alike...how to use them." --Richard Henry Lee

"A well-regulated militia, being necessary to the security of a free State, the right of the People to keep and bear arms, shall not be infringed." --Amendment II, Constitution of the United States