Go in at about an hour or half an hour before your court date is expected to start. Talk with the DA prior to going in and tell him/her the situation and ask if it could be dropped. Usually they will do it if you are well spoken and dont come off angry. If not, ask if they will reduce it. It will probably go on as an "Inproper Lane Change" which I dont beleive will give you any points off your license and the ticket isnt much.
I feel your pain though, I honk/flash lights at all people that cant use a turn signal. Even the cops (who are most guilty). I wish I could site them for inproper lane change!
You were just targeted is what it boils down to. The fact that you had a gun was more reason for them to hold you to insure you arent packing anything else, registered or not.