I know they will refund money depending on the issue (sent to the wrong person for example). If they can confirm that it was a mistake, they will usually refund it.
I have not heard of them just refunding money because someone ‘files a claim’ (like PayPal does), but the bottom line is that none of these companies are going to be “pro-gun.” If that’s introduced into the equation at any point, I would say all bets are off (as a buyer or a seller).
A pretty safe rule of thumb… if you’re concerned about a buyer pulling some funny business, or have to ask if a certain payment method is safe, it’s probably not worth the risk.