Both the sights and silencer had been removed by JB that night before he put the rifle on the settle. The sights are a fiddly thing to attach and has to be done with a screwdriver,so that job wouldn't have been attempted.
Why would Bamber remove the silencer before going outside to shoot rabbits ? It's supposed to have the silencer on for shooting rabbitts.
Or are you saying he went outside with the silencer attached, then took it off and put the silencer away when arriving back inside. However still left the rifle out in the kitchen? Again why bother doing this, as the rifle still fitted in the gun cupboard with the silencer attached.
Is this what Bamber told you ? He didn't tell the police this. Otherwise please provide a source.