For your reading enjoyment, their policy towards firearms as of 9/8/2015

The PayPal User Agreement states that PayPal reserves the right to limit an account for any violation of the PayPal User Agreement, including the Acceptable Use Policy.
Under the PayPal Acceptable Use Policy, PayPal may not be used to send or receive payments for firearms or weapons, which include but are not limited
to:
Firearms – Includes all rifles, shotguns, and handguns, whether they are intended for use in sporting, as collectibles, or as curio and relic firearms. These items are prohibited regardless of their present working order.

Firearm parts – Includes, but is not limited to, receivers and frames, silencers, kits designed to convert a firearm to automatic firing capability, a magazine that can hold more than 10 rounds, multi-burst trigger activators and camouflaging firearm containers.

Ammunition – Includes ammunition with propellant, such as gunpowder or blank ammunition. Ammunition is defined as ammunition or cartridge cases, primers, bullets, or propellant powder designed for any firearm.

PayPal allows transactions for paintball guns, blank guns, and air-soft guns as permitted by law in the applicable jurisdiction. These items must display all markings required by law, must not be convertible to shoot a lethal projectile, and must not include blank ammunition.