In theory, yes. Royal Mail (Absolutely NOT Parcel Force) claim they carry airguns and parts UP TO 2 KG internationally.
Check their country guides.
Make sure you know the difference between Prohibited and Restricted and understand that Post Office Counters, Royal Mail and Parcel Force are different firms..
The Royal Mail
RESTRICTED guide for Portugal
Guns for sporting use
Guns intended for sporting purposes - including Section 1 (e.g. hunting rifles) and Section 2 (e.g. shotguns) firearms, low-powered air weapons and their component parts - may be sent
in compliance with UK law and subject to domestic controls on the possession of firearms. Antiques, deactivated and imitation firearms are also permitted. When sending deactivated firearms include proof of deactivation.
Items that appear to be prohibited weapons may be subject to additional checks and delays. Please see www.royalmail.com/prohibitedgoods
Use 1st Class as the minimum service. The sender’s name and address must be clearly visible on the outer packaging.
The PROHIBITED guide
Including Section 5 firearms (e.g. handguns, machine guns), CS gas and pepper sprays, flick knives,and other knives that are banned knives under UK laws, tasers and stun guns. Items that appear to be prohibited weapons may be subject to additional checks and delays.
Guns for sporting use, including Section 1 (e.g. hunting rifles), Section 2 (e.g. shotguns) firearms and low-powered air weapons may be sent
in compliance with UK law and subject to domestic controls on the possession of firearms. Please see www.royalmail.com/restrictedgoods
In practice, Post Office Counters, Royal Mail and Parcel Force are an utter, utter shower of shite and don't know their own different rules.
You are supposed to go to a Post Office but Post Office Counters will eff it up and either tell you guns are totally prohibited or get you to send it via a Parcel Arse international service (because Royal Mail don't do over 2KGs) where it will be impounded at the airport and purposely damaged because guns supposedly can't travel by air or by Parcel Arse.
Been there, got the T shirt.
, however, are by law supposed to transport guns.
In Black and white it says you can send guns and parts abroad by Royal Mail up to 2 KGs. Just make sure you print it out and show it to the counter Mon... eeer.. "staff".
Most rifles weigh over 2KGs though, so send it in bits! It's a typical british Clusterfukc that makes british shops and mail order firms uncompetitive in the EU.
If you are a member of BASC, I suggest that you get them to help you send it. I now live abroad and am not a member but I would like to see BASC purposely try to send send a rifle , pistol or part abroad and to give Royal Mail a rocket up the Jacksy when they cokc it up.