Threatened shopkeepers used 30-round magazines to fire warning shots and avoid taking lives. Bans on high-capacity magazines (variously defined as those holding more than ten, fifteen, or twenty rounds) seem to be part of just about every law to ban assault weapons. The rationale is to prevent the ability to engage in killing sprees like the one on Friday in Connecticut.Would a ban on high-capacity magazines (and not just a ban on new manufacture, as the 1994 federal law provided) make any difference in these massacres of the unarmed? I am hard pressed to see how. Detachable-magazine pistols and rifles...