That said, I think people need to recognize that in many aspects what's happening is connected to societal issues that gun control and gun regulations will have very little impact on - remember, even in Japan somebody could make some kind of battery ignited home-made shotgun and kill Shinzo Abe.
Countries with strict gun control enjoy far lower rates of firearm accidents, suicides, and murders. IMO it's clearly worth the tradeoff. Very few of us live in a place where only guns can solve our problems.
The fact that occasionally someone goes to great lengths to kill doesn't mean we should make it easier for everyone.
Congress around 1982 had the Library of Congress issue a study about this in great depth, with millions of citations to historical documents, which give ample evidence and quotes. You may have to dig to find it, but it's a good read to gain more understanding.
Also the second militia act of 1792 actually required all able bodied men to own guns, and this was the law for well over the following century.
The founders had no qualms about everyone having arms.
The word has many meanings. Learn which one the phrase in the Constitution is using.