Mike,
If the moderator needed the coupling as per image below (please see text, red lines), this could be 'the Holy Grail'.
(A) - Anshuzt rifle, .22 semi-automatic rifle (Bambers)
(B) - Parker Hale Silencer (belonging to Bamber rifle)
(C) - Bruno rifle , .22 bolt action rifle (Pargeters)
(D) - Parker Hale Silencer (belonging to Pargeter rifle)
Is A B and D compatible? IF ANSWER 'NO'
Is C B and D compatible? IF ANSWER 'NO'
Due to a 'coupling' /adapter required then the Police can't say ''there was only one rifle''.