I've handled a lot of mid-18th century British guns and I've never seen one with a Biblical quotation on it. For a number of reasons this was very unlikely. The subset of the population who would likely have been intimately familiar with the Bible were the dissenters (non-C of E Protestants) and relatively few of them belonged to the class that would have owned a fowling-piece. One of the contributing factors to Birmingham's success as an arms making town was the fact that it was unincorporated and therefore not subject to the restrictions of the Clarendon Code, a set of laws placing restrictions on dissenters.
There were plenty of wealthy dissenters but most made their money in trade, as other professions were forbidden them. (The Galtons, Quaker gunmakers and Josiah Wedgewood, the potter come to mind). As such, they were rarely members of the landed gentry who were the only market for fowling guns. There was no public hunting land in Britain (and there isn't any today) so unless one had land or knew people who did, hunting was not possible.
