I think it depends on what kind of gun stuff you deal in.
I have over 300 transactions for reloading tools on ebay so most of my transactions are for some sort of gun related stuff.
I have also bought knives and car engines on ebay.
I have never had ebay object to any transactions.
I have also paid for a number of transactions involving reloading components like brass and bullets and so far I have escaped their attention.
I am not sure how paypal establishes what is permitted and what is forbidden but as long as you are buying stuff from ebay I don't think they have room to complain.