I agree with JonathanLivengood and would like to state the issue a little differently: you omitted an option that we might call 2b: reduce the effectiveness of available means to kill. If guns are made less available then even if other effective means of killing are available they might be ones that lead to fewer deaths. One thing about guns of the sort used (e.g.) at Sandy Hook is that someone armed with one can kill an awful lot of people in a short period, without putting himself[1] in a vulnerable position by having to stop to reload.

Note 1. Somehow, it almost always is a "himself" rather than a "herself". This paper has some interesting thoughts about why, though various stylistic features will probably be unappealing to some LW readers.

[EDITED to fix a formatting glitch caused by my preferred footnote format.]