An electric lawnmower and a pair of nail scissors can both be used for cutting the grass, right? It's the human being who cuts the grass, not the innocent lawnmower.
That's a different version of the argument I right now read everywhere on the Internet: Some version of the guns-don't-kill-people-people-kill-people. I think it shows the differences in effectiveness.
That's why guns are what we should talk about when it comes to horrible events such as the Connecticut school massacre. Especially semi-automatic guns.