From ParcelForce website
Arms and Ammunition All firearms,
other than low-powered air weapons sent within the UK (air rifles, air guns and air pistols),
including imitations and antiques; paint-ball or toy guns; taser guns; components of firearms and all other items similar to, or resembling, the foregoing are prohibited. All ammunition other than lead pellets and other air gun and airsoft projectiles is also prohibited.
Arms and Ammunition - low powered air weapons Low-powered air weapons (air rifles, air guns and air pistols), together with lead pellets and other airgun and airsoft projectiles, can be sent but are subject to the following conditions:
- These items must be sent on an express48 service only
- These items must be sent via the Post Office only, and presented at the counter
- Enhanced compensation cover is not available
Yes
No
The 'Yes' 'No' on the right is for
UK=Yes
International=No
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RoyalMail
- UK - Allowed in the mail, see restrictions and packaging guidelines below:
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.
- Use 1st Class as the minimum service.The senders name and address must be clear on the packaging. Low-powered air weapons which exceed the Royal Mail size restrictions are accepted by Parcelforce Worldwide, using express48 via the Post Office.
- Guns must not be loaded.
- Air weapons with an integral gas cylinder that are de-pressurised can only be accepted. Air weapons with gas cylinders that are pressurised are prohibited
- Air weapons with a pressurised removable gas cylinder which is still attached are prohibited
- Must be packed in rigid outer packaging suitable for the gun size and weight, for example a fibreboard box, with sufficient inner packaging to prevent movement during transport.
So you might be OK with RoyalMail but depends on the knowledge of the particular handler.
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As an example for other carriers, MyHermes lists this under prohibited items:
Weapons and replica weapons – Including decorative, deactivated or air powered weapons