There weren't guns in Bible times, but there certainly were weapons. Wayne Grudem tackles the issue in his book, Voting as a Christian: The Social Issues, pp. 93-107. Grudem also discusses the subject in this podcast taken from a Sunday morning Bible class. An outline of his talk may be found here. Dduardo D. Co Jr. recently wrote a paper for a Theology course in Asia Theological Seminary in the Philippines which draws heavily on Grudem in its final section.