What is Stuart's Gun?

As a law enforcement officer whose duty was to keep law and order, Stuart was issued a gun. Thus, the gun itself is a symbol of law and order. Drew uses this gun to shoot Stuart.There were other guns in the house Drew could have used, but Drew chose the issued gun on purpose. Stuart was a perpetrator of abuse and rape. He showed no respect for law and order in his "own house." Drew's decision to use that gun is symbolic.

Also, Stuart had used the same gun to teach Drew how to shoot. He made fun of Drew during the lessons because Drew's shots were so far off from the target. Drew killed Stuart with one shot to the head.