Who has a Sect 5 air rifle ?
The latest Firearms Guidance form the Home Office contains the following:
2.43 The Rules provide that any air weapon is ‘specially dangerous’ if it is capable of discharging a missile so that the missile has, on being discharged from the muzzle of the weapon, kinetic energy in excess, in the case of an air pistol, of 6 foot lbs or, in the case of an air weapon other than an air pistol, 12 foot lbs. An air rifle with a muzzle energy in excess of 12 foot lbs must be held on a firearm certificate. Any short air weapons (which either have a barrel less than 30cm in length or are less than 60cm in length overall), with a muzzle energy in excess of 6 foot lbs are prohibited firearms.
This has been legislation since the 97 amendment banning short weapons.
If your barrel is less than 30cm it's Sect 5, if the overall length is less than 60cm it's Sect 5.