If you want to buy a firearm off here you can’t rely on the PayPal protection. I would suggest you evaluate the persons feedback on here or other places like eBay etc. Ask them to FaceTime with you to verify that they are who they say they are and they have the firearm. Get their phone number, email and physical address and do your due diligence to make sure that info is legit. If all that checks out, it’s fine to pay with FF but leave the comments blank. I have purchased a rifle successfully off Rokslide like this. Overall it should be doable but again, if there are any alarm bells, back out of the deal. If the seller is pressuring you in any way, that is a red flag in my mind. Honestly this advice goes for any high dollar item whether it be optics, bows, firearms etc.
Luckily I feel like I haven’t seen scammers trying to scam people on firearm deals as it’s probably territory they don’t want to be in but I’m sure they’re out there.