There is a video clip which shows this to have been the case where the trigger could have been reached with the silencer fitted to the guns barrel...
I haven't seen the video and you haven't posted a link to it here. Can you do so or post a still from it or a photograph that shows Amy's finger on the trigger while the sound moderator is on the rifle? Also, can you post Amy's height or any photograph from which her measurements can be deduced?
I think the whole debate about whether Sheila could have shot herself with a gun with silencer attached might have stemmed from the photograph which shows a gun propped against the bedroom window. If you look closely at this gun it appears to have a silencer attached.
The debate started long before the photograph was released. I can't see a line across the barrel where the sound moderator would start, and the overall length of the barrel appears to be too short for a sound moderator to be present. There is a slight difference of appearance halfway along the barrel, but that can't be due to a sound moderator, as photographs of a rifle of the same size with a sound moderator fitted show that the join is not halfway along the barrel, but only about a third of the way along. Why do you think the sound moderator is there?