You need to set up an account. It's pretty easy. Now, sometimes, depending on the receiving FFL for the buyer, you may need to ship the gun from a local FFL. It's also usually cheaper if the gun you're selling is a handgun.
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Never initiate force against another. But should someone do violence to you, retaliate without hesitation, without reservation, without quarter, until you are sure that he will never wish to harm - or never be capable of harming - you or yours again.