This is a classic discussion of the two routes to persuasion - standard in psych, business or marketing.
Google it - for instance:
http://www.ciadvertising.org/studies...pagethree.html
and see many more lectures on it.
The emotional route is easier for most. BTW, IMHO - it is a risk for the RKBA.
Very powerful images of dead kids may have more impact that some RKBA advocate discussing why he should own the same 'assault' rifle that a nut used.
Read up a bit before you try the emotional appeal.