A “22” is primarily for shooting small animals or target shooting. It isn’t the sort of weapon you would use to shoot people. For example, it’s the largest rifle allowed in Boy Scout camps. Do you really understand rifles?
Giving a gun to someone who is untrained is suicidal. Shooting a gun, especially at a moving target who is shooting at you, is not
a game. Are you confusing reality with a video game? Remember that in the real world, there is no reset button to give you additional lives.
Note that our rabbanim have for many centuries have insisted on learning Torah rather than focusing on vocational skills (note that shooting terrorists qualifies as a vocational skill). If we need armed guards (and at this point, no American Jewish school has ever been attacked), we have a variety of methods to address the matter. Note that the mass shooting attacks against schools in the US have all come from people with some connection to the school, suggesting that we need to defend against someone who is going radically off derekh.