A lot of the information recovered from Police Forces, especially surrounding it happened on "Someone Elses Watch" time, will spill out stuff like this, totally inaccurate as you have uncovered, because it is simply word of mouth from the longest serving person in a position, who can remember to the best of his or her ability.

Not good enough really. Lets just say that one of those rifles was used in a mass killing regardless of the location, there would be a massive enquiry to establish how these rifles became unaccounted for!!!
I have always favoured a National Firearms Register, which is in effect what should happen now as they are all, finally, on the same software.

However....................... things that went on in the past, seem to have missed a total beat somewhere, and not sure when it occurred either!

Certainly today, all Police weapons are guillotined after service.