The Ketlands, in this case the partnership of Thomas Ketland and William & Alexander Walker, began large scale exports to America around January of 1793. Until then there were no shipments of British guns or gun parts because they had been embargoed in 1775 and the embargo was only partially lifted in November of 1792. Some of their shipments went to Philadelphia but they also went to Savannah, New York, Boston and even Florida. The person most often associated with the trade is Thomas Jr., in Philadelphia, but he went bankrupt in about 1803 and thereafter all of the T. Ketland shipments went to other parties, notably Simon and Alexander Walker. Simon and Alexander were sons of TK's partner and were also located in Philadelphia. In any case, K locks were very common, a staple of the hardware trade all over the east coast so I don't think anything can be learned about location from the lock aside from the fact that it was made in Birmingham.