Can't see it myself. The only evidence remaining is the location of the casings and the odd blood stain. There is no trajectory evidence per sé. The accumulated evidence points directly at Jeremy Bamber and that is unchallengeable imo.
The evidence at soc by way of blood stains, casings, distance of shots, trajectories and wound tracks show exactly what happened: perp was upstairs and NB was first shot twice in the face whilst he was on the landing facing into the bedroom with perp stood inside main bedroom firing at NB on the landing.
In the case of MM forensic scientist talked about a case where the police bought a house to preserve blood stains which in the end caused the case to take a completely different direction. In this case blood stain analysis was in its infancy and wasn't used at trial in the way it would be today. I believe there is still some potential for this aspect to be reevaluated based on soc images.