how does one go about buying a used firearm? i assume, as a first step, the serial number of the firearm needs to be checked with the FED. (i understand gun shops can do this for you for a fee.) after this, what paperwork is next? may deed of sale ba yan? is it like applying for a new firearms license? also, what things should one look out for? what needs to be checked with the gun before committing to buy? thanks in advance for your inputs.