Are you serious? Did you really inherit 400 oz of gold. Or do you know of someone who did?
If you did, I would be extremely careful about selling it. It is worth a whole lot of money and many people would think of ways they could cheat you or rob you. I would go visit a reputable dealer and speak to them in private and only if you feel comfortable, you can proceed to arrange for the sale.
But I think you must be joking or at least asking a hypothetical. If not, be very careful Do not ever advertise that much gold for sale on Craigslist for example. You can just bet that someone will try to take advantage of you and violence would not be out of the question.