According to trial testimony. David Boutflour takes a close look at the knurled end of the silencer and attempts to unscrew it. But does not recall seeing a grey hair.
Once Peter Eaton hands the silencer over to the police, he points out a grey on the same knurled end that DB looked at two days ago.
Since DB noticed the paint and the blood, how did he miss the the grey hair? On a black silencer a grey hair would stand out.
Did he fail to notice it because it simply was not on the silencer at that point in time?