I agree this would have been far more likely had Sheila been the killer. I think Jeremy was worried that Anthony Pargeter would realize a silencer was missing, given that they had both been shooting together outside the previous weekend.
That was Anthony's visit on the 26th. July 1985. The rifle could not easily fit into the gun cupboard with the silencer attached to it. I make the point here:
https://jeremybamberforum.co.uk/index.php/topic,10382.0.htmlThe gun cupboard ordinarily had lots of stuff in it: boxes, ammunition, other guns, and what not. The rifle would not be naturally positioned like it is in the photograph. It is a contrived photograph taken by the police to prove a point because Jeremy had averred that he would have taken off the silencer when stowing away the rifle. Surely you can concede that Jeremy at least has a point in this regard?
I am not saying that Anthony Pargeter lied in his statement. I think it is more likely that he has misremembered what he examined on the 26th. July when giving his statement to police in August. It's an easy mistake to make. In any event, to be clear, I am doubtful that Anthony Pargeter ever saw a silencer on that rifle.
I accept this does not answer your point completely. Even if Anthony Pargeter never saw the silencer, Jeremy could still have been concerned that the silencer would be missed. But if Jeremy had the presence of mind to realise that Sheila could not reach the trigger of the silenced rifle (actually, she could with her toe, but that's perhaps beside the point), wouldn't he also have had the presence of mind not to allow family members to have the key to the farmhouse with the silencer still there? Wouldn't he have arranged disposal of the weapons himself?
Furthermore, if Jeremy disposed of the silencer in the gun cupboard while carrying out the crime, why was no blood found on the den carpet or in the gun cupboard, other than on the silencer itself?
This is before we get into the whole question of whether the silencer was used at all. After the 2011/12 CCRC rejection, new expert ballistic evidence was obtained that suggests a silencer was not used in the killings. I also wonder how Fletcher's pull-through test could reveal no blood in the rifle barrel if the silencer was supposedly used to fire contact shots before Sheila was killed? Simple gravity would dictate that there should be blood in the rifle barrel.