- give the SAG a new model, with some kinda readout that shows what mode it's in
have the SAG as an item, striking out one of the slash commands- cycle through modes with right click, striking out another command
make the gun use raycasts (because everything's better with raycasts)
God damn you're almost as bad as Space Guy. You should really check whether or not something is already in the mod before you think that it isn't.
I don't see why I'd use a model because A) I can't model a gun handle/trigger for my life, B) it would be yet another model for players to download, and C) I don't see how a readout would be useful, if you forget what mode you're in you might as well just enter the command for the mode you want. I do like your idea of cycling through modes with a button, though.
idiot nooby noob u have to EXPLAIN IT and have a pic of it freak

I explained it thoroughly and mentioned it looks like a blue gun. This is a tool, not a weapon, I don't see how a picture would help at all.
Does the bomb/nuke only damage bricks?
Yes, nothing that this gun does (minus, arguably, the fact that you can use the wand mode to push players as an admin) will damage players/vehicles.