There's a lot of debate going on right now about what the results of the Virginia Tech massacre might have been had just one targeted student been armed.
Here's a way we can approximate real world results: Stage an Airsoft mass shooting.
Gather around 20 friends or so. Pick a room to conduct the test. Everyone should have protective gear. One person should act as recorder/tally keeper, off-limits to the action.
One person will act as the shooter. He will enter the room where everyone else is seated in simulation of a classroom setting. He will block the only exit and begin shooting. In order to be faithful to the Virginia Tech scenario, no one will fight back. You can run, you can duck and cover, you can play dead, you can plead, you can pray, but you can't counterattack. Feel free to add to the pandemonium, though. If hit, raise your hand and remain in place.
What were the results?
Now we're going to repeat the test, but this time, one person in the room will have a concealed Airsoft pistol, and will draw and fire it at the shooter when they think they can. Again, to be faithful to real world conditions, this person should have practiced with the "weapon" beforehand to approximate the skill level of a trained and knowledgeable gun owner. And to keep things as realistic as possible, don't tell the shooter or anyone else this scenario is planned. THIS IS IMPORTANT. Let them get through one massacre, and then tell them you want to do it again to reconfirm the results of the first test--that way, the shooter will be just like Cho, or Harris or Klebold--he won't be
expecting resistance from his prey--and the "victims" will likewise not have cause to react differently.
What were the results this time? If the person shooting back is hit, could he likely have continued firing? Note that this does not guarantee everyone will survive, or that there won't be collateral damage--what we're looking for is simply a difference in raw numbers of people shot. The recorder will call a halt to the action when the initial shooter is deemed stopped, and ask everyone to remain where they are and report if they've been hit and where.
Then we can up the ante. Pick a new shooter, again one who doesn't know there may be armed victims. Now add another concealed carrier in the classroom, or maybe a couple more--after all,those opposed to armed defense would have us believe the more people with guns, the worse such situations are likely to become--why not test that theory as well? As the number of concealed carriers goes up, what happens to the number of victims?
Feel free to come up with variations and rules of your own--this is just a rough idea at this stage. If anyone actually conducts these or similar tests, I'd be interested in hearing the results.
Disclaimer: If you do this, I'm not responsible for any consequences. Here's some information you may find useful, but I ain't vouching for it. It might not be a bad idea to let local "authorities" know about your intentions so you don't get mistaken for real shooters and shot. Even firing Airsoft equipment may be illegal in some jurisdictions/prohibited in some locations. You may want to get everyone to sign waivers, but that's not legal advice. Here's an online manual I found-- follow its suggestions at your own risk.