I've just been looking at the Inspection Certificate accompanying my 1995 BSA 240 Magnum air pistol which is stamped as passing for accuracy of 5 shots at 25 yds.
It doesn't state the accuracy criteria, but I doubt it was tested at 25 yds and is probably a standard air rifle certificate used for both rifles and the pistol. It would be
interesting to know what the accuracy requirement was for air rifles and pistols and the associated failure rates.