I guess I am fortunate to have a friend who is a part of GB. He tells me fraud is extremely rare, however mispresentations or missed defects do occur.
He also tells me many sellers have been screwed because buyers will remove a part(s) from a gun or replace a part and send the gun back to the seller.
Then the fireworks begin.
I concur with Rodfac
on his cautions especially the use of USPS money orders.
My prefered method would be to use the credit card as of the protections you have. Yes I realize some sellers have surcharges of around 3%, but a credit card is a safety net.
Also be aware of those with very few sales.
BE CAUTIOUS OF "AS IS, NO RETURNS".
Auction Arms, does not have the "AS IS" problem. Sellers must allow an inspection period.