This is your idea of a perfectly clean foot? 
David posting a picture of someone else's foot the CT published is not going to change the situation.
While still alive Sheila could not have fired 24 shots & re loaded twice, then removed 20 pieces of evidence showing she had done this. There is also no reason why she would want to.
After killing herself with two bullets, it would again be impossible to do this.
Either Bamber shot her, or Mike's & Sherlock's suggestions it was RB, AE, a hit man, random stranger, SAS esq hit man team shot her.