I use gun.deals to search for vendors. Have used various places to order firearms and accessories, based on that search engine.
I've not been burned yet. And frankly, I am not that worried about it. If my order takes a few extra days to ship, who cares? And a fraudulent charge isn't going to bankrupt me. No offense, but there are bigger issues to consider.
Most recently, Gun Pro Deals had the best prices for what I wanted. If I had a concern, I'd simply call the vendor to confirm inventory, shipping, etc.
