The basis for the suit would be what? If you were arrested and you were carrying legal that would be cause for a suit. If you were injured that would be cause. You may, MAY have cause for an official complaint or suit if the exact circumstances did not warrant getting placed on the ground. Good luck with that one. You would have nothing at all to go on regarding having the cop hold you at gun point for some period of time until the situation is made clear and safe. I can't imagine it would not involve getting you out of the vehicle.
The legal standard for the actual use of deadly force, that is actually perforating you with one or more bullets, is means/opportunity/intent. If the guy has no idea you have a gun and you reach for anything near it how is he to know you are not reaching for the pistol? This action would be just plain foolish. You have now met the bar for MEANS you clearly have a deadly weapon. You have met the bar for OPPORTUNITY, you are reaching for it (he can't possibly be a mind reader). You have not yet SAID you are going to use it, but it could be argued that reaching for it does display the intent to use it.
At any rate, any reasonable cop is going to absolutely stop further action on your part. Again, given those circumstances, the suit is a no starter. Reaching toward a weapon during a traffic stop is a ridiculous thing to do.
"A Liberal is someone who doesn't care what you do, as long as it's mandatory". - Charles Krauthammer