This movie was in color, It was most likely made in the 80’s, I seen in mid to late 80’s
It’s about this teenage boy who finds a crate that fell off a military transport train.
Inside the crate is a ray-gun type weapon (I think it had a backpack)
He goes around shooting things, If I remember he kinda gets drunk with power.
Also I think there is a problem with the design and there is a risk of the power source blowing up or something.
In one scene he’s talking to this man, his principle iirc, he says something like “Hey *blank* you left your lights on your car”, and then he blows it up.
I’ve tried using google to find the name of this movie and kept coming up with laserblast, but reading about that movie it says the gun turns the boy into a monster, Im pretty sure that didn’t happen in this movie, So I don’t think it’s laserblast.