The inquest into the Horden shootings has been shown the gun that Michael Atherton used to shoot himself and three others dead on New Year's day last year.
An officer at the inquest also said that while steps have been taken to make gun licensing at Durham Police more robust, he believes there should be a review of the national guidance given to police forces.
Watch the full report from Frances Read below.
The coroner has ruled that the deaths of three members of the same family, and their shooter, could have been avoided.
An inquest has heard how a man who went on to kill three members of his family before turning the gun on himself had been warned by police.
The inquest into the deaths of a man who shot himself and three members of his family on New Years Day 2012 has been taking place today.