Show him some love and take him out places often, teens can often feel alone typically around this age. He probally woulnt like it or want to go anywhere but just show him that everythings okay and no ones "against" him.. Possibly get him evaluted for anger disorders ext. Hes rebelling against you in a way thats not exeptable in any means.. Also talk about cyber school with him or other options. He could be getting bullied and this is his way of acting out. I dont know your son personally so its hard to say over a computer but try to understand his actions more rather then sending him off some where, A mental institution or boot camp is far from the answer try to do things that makes him happy,, If you can make him happy maybe the behaviors will stop, Im not putting you out as a bad parent as obviously your concerned about him but just try some different options rather then shipping him off.
If you are aware he is taking weapons to school you should inform both school authorities and the police. Your description indicates he is on a course to the juvenile correctional system.