Courtesy of the YouTube site:
The controlled study documented in these videos show that concealed carry permit holders are fooling themselves if they think they will be able to react effectively to armed aggressors. Most CCW holders won't even be able to un-holster their gun. They will more likely be killed themselves or kill innocent bystanders than stop the aggressor. For more details, see "Unintended Consequences: Pro-Handgun Experts Prove That Handguns Are a Dangerous Choice for Self-Defense.
This is longish, coming in at a little less than ten minutes (And this is just part one), but it is well worth your time and something that you can Facebook and tweet to all of your pro-gun relatives and friends that might just give them a few facts to chew on for a change.