Typical anti mental illnes. Projection.
They (anti's) feel so out-of-controll internaly, they assume that if they have a gun they'll use it as any impuse dictates. They also incorrectly assume that everyone else, i.e. law abiding gun owners, are the same as them. Anti's can't fathom that they're the one with the problem.
It's also part of the typical anti/liberal persona. They're so ashamed of their internal hatreds and desire for power, they manifest their anger and desire for control through a mask of do-goodisim and wanting to "help" people.