England and Wales
Air rifles are regarded as firearms when used or carried for illegal activities. See https://basc.org.uk/codes-of-practice/air-rifles-code-of-practice/#:~:text=Always%20shoot%20well%20within%20your,three%20centimetres%20(1%C2%BC%20Inches).
Air rifles over a certain bore need a licence and so should not be given to a non licence holder.
If you have a 'no firearms' rule you can reasonably refuse any posts for air rifles.
There are age restrictions on both purchasing and carrying air rifles in public places.
There are also age restrictions on supervision of young persons with firearms.
It is recommended that if you do allow a post, that you remove any reference that there may be to shooting live creatures, as otherwise you will be deluged with complaints.
It is also illegal to shoot protected species, and domestic animals with the exception of dogs (when chasing farm animals) . Most birds are protected too, see f4bscale.worldonline.co.uk/gunlaw.htm
Groups based in country areas will be much more relaxed about air rifles that those in the cities.
From 31 December 2016 anyone who wishes to use, possess, purchase or acquire an air weapon in Scotland will need to have a valid Air Weapon Certificate, or a temporary permit such as a Visitor Permit, unless they are otherwise exempt under the legislation.
The requirement applies to most air weapons with a muzzle energy exceeding 1 joule (0.74 ft/lbs), and up to 12ft/lbs (16.27 joules) for air rifles or air guns, or up to 6ft/lbs (8.13 joules) for an air pistol. There are some exceptions, for example for paintball guns or airsoft weapons.
See also Guns and replicas