The right cherry picks the constitution as well. Also, it can be amended. If it becomes clear that the over supply of guns and the childish way with which the less responsible or less honest gun users is a problem then this can change. Pointing to the 2nd amendment isn't a silver bullet argument. There are very few of those.Except, that you should consider incorporating the Constitutional aspect and the historical aspects into your reasoning as well.
The left has very little loyalty to the constitution as written. When you tell the left wing "but the constitution says..." I honestly believe most of them roll their eyes. I think most conservatives know that. That's why I made my argument elsewhere.