I used to buy and sell via GB a lot.
Once I started hanging around on internet forums, I started doing all of my dealings there. A lot less headache when you can swap phone numbers, have an actual conversation and nobody is skimming fees off of either party. Plus, that way you can determine who you sell to or not. If the buyer doesn't come through with the goods, you don't have to go through a lengthy appeals process to get your money back.
If what you have is desirable, then list it here and other gun forums that you have frequented. If you are worried about getting scammed, just remember, as the seller you have the actual goods. Don't ship it until the money is in your account.