Royal Mail and the Post Office are not the same company. The Post Office were stating different rules for the Royal Mail than what Royal Mail publish on their website.
Agreed. And you shouldn't have to lie or withhold facts in order to use a service in the way that it is advertised by the service provider.Apart from that it's pointless to lie or misrepresent your item, it's legal to send a low power airgun, or parts of one & if you need to claim the compensation you're still going to have to prove what it was & what it was worth, at which point the rules for a gun will apply.