A gun safety device includes a barrel plug assembly having a first compression member, a second compression member, an expansion member, a joining member, and an adjustable extension rod assembly. The expansion member is sandwiched between the first compression member and the second compression member. The joining member is operatively linking the first compression member to the second compression member. The joining member is adapted to draw at least one of the compression members towards the other compression member. The adjustable extension rod assembly extends from the second compression member.