Would you be more likely to do so if the government offered some financial compensation -- say $50 / gun? $100 / gun? Maybe scale the amount offered to the size / expense of the gun, so that essentially, you'd get roughly half back of what you paid for it originally?
I will tell you right now, I'm willing to have my taxes raised for such a program. I'm willing to donate cash, straight up, to get some guns out of my family's neighborhood.