With your integration between Parcelforce and Shiptheory it's possible to send firearms via enhancements. You'll see the following three options:
Section 1: This is for Rifles, Over 3 shot Shotguns and FAC Airguns
Section 2: This is for standard shotguns
Other: This is for Airguns
When using this enhancement, you'll need to ensure that before using, you've already spoken to Parcelforce to enable this for specific services and account departments.
If you have any questions or issues when sending, please Contact Support.