Is it realistic to believe that a teacher could effectively defend against an active shooter, using an AR-15, armed with only a handgun?

Why not? In a close quarters combat situation, the accuracy of the rifle is negated by the proximity to the target. In a classroom you might be a max of 50 feet from your target. In a hallway your odds go down with a handgun, but a trained shooter should be able to do just fine.

LCPL: You bring up some valid points. As a retired military officer (and former Marine), I share your concerns; however, a well-trained, motivated, and caring teacher or member of a school staff can save lives by deploying a firearm to stop an imminent threat of great bodily harm or death. If my kids or grandkids were in a school where an armed assailant is murdering innocents, I would prefer a teacher or staff member that is armed at least attempt to stop the threat. Most active shooter incidents are over in less than 5-minutes, which means even the most fully staffed and aggressive police agency may not arrive on time to take appropriate action to save lives. Thank you for your commentary on a very important topic that is getting more important as these deadly encounters increase in number and magnitude. Semper Fi! COL L

At ranges greater than 50 meters (the average effective range of a pistol and what you described in your post) it is true that pistols will have little effect (though there is one handgun I have fired in the past that has an effective range similar to a rifle). However, in a school shooting situation, it is more of a close quarter combat situation. In this situation the increased distance of the rifle (Long gun) is mitigated by narrow passages and many doors and corners that a smaller weapon are not affected by. This is one of the main reasons the military moved from the "fixed stock" of the M-16 to the collapsable stock of the M-3, it provided more maneuverability in close quarters while maintaining the range needed for open field combat.

I have posted in another thread, that a good response to the increased violence (other than returning prayer to school, and deregulating firearm sales) is to have a discharge option for every service member to receive a Federal concealed carry permit with the same carry privileges as most Federal Law enforcement officers. This would be a Force multiplier for any local law enforcement agency and provide quicker response times to active shooters (in most cases).

Arming teachers is a great idea, and they should get a special pay bump and paid recurring training for taking on this extra duty. Teachers have the home turf so they know where all the hallways and exits are. Teachers can be trained to work as a team to move students to safety while defending the retreat. People may complain about having a school with armed teachers as they want their kids to always live in a world of puppies and unicorns but this is just not reality. Personal defense cannot be outsourced, the courts re-confirmed this with the latest FL shooting. The job of the police is not to defend you, but to just take evidence after they mop your bloody unarmed body off the floor.

Look at Israel, if I remember correctly they have armed teachers and it works well.

I don’t know how realistic it is, but just the thought of going up against an armed teacher might be enough of a deterrent to maybe prevent the attack altogether.

My opinion is that if teachers wish to be armed then they should be allowed to. Would you want to go against an AR15? No and I wouldn't either...but the alternative is to be shot with no option but to cower or hide and hope that the shooter doesn't pick your room. After the theater shooting in Colorado there were some crazy liberals who were spouting that if a citizen had been armed then he might have shot someone by accident....the option is to be shot like fish in a barrel. I'll take some chance orver no chance any day!!

Yes sir it is realistic a teacher can defend no matter what type of gun is used. The two factors that decides who live or die, is who has the jump and the fastest trigger pull. What people are getting confused about is, the gun is only used to defend the classroom just in case that active shooter decides to enter. You have to understand teachers don't have the extensive training like law enforcement and some military personnel have to go on the offensive and engage....... Their primary job is to shelter in a classroom or other safe area and defend if need be......

I believe the objective is not to make teachers armed hunters but to give them the means to defend their classroom should need arise. That takes less training than going toward the threat and could be effective in surprising an armed antagonist breaking into a classroom.

Only one in ten will shoot to kill when the chips are down

I should hope the ROTC instructor should be able to do it.