cant imagine actually going to someone to finance a gun.. First, if you can save for it, that is the best way to go. Second, if you need it that bad, sell something to get it. third, it you still need it and cannot afford it, pull out the credit card.
Unless it is a once in a lifetime gun that is worth many thousands of dollars that you are getting REALATIVELY cheap (not so many thousands of dollars) I would never fathom taking a loan to get a gun.