Well, I think we know that Perkins was not importing "the entire lock already finished"--at least once the Revolution began. The inability to find gunlocks in early America after 1775 frustrates nearly all the new production that the colonies attempted to foster. I've described this above in Pennsylvania's case, which I know best. (The Congress's "Secret Committee," called that because it met in private rather than in public, tried to import 20,000 gunlocks at one point.) Gunlock factories were established in Philadelphia and Trenton and I think in New York and Connecticut and elsewhere. Here is John Nicholson's plan for one of these factories:
A Shop to contain three forges for forgeing Locks, with a good sett of tools to each, and a shop or shops to contain forty Lock filers, with a good sett of tools to each, suitable to the part of the Lock they have to file, with a forge for every ten Lock filers to harden & temper the Springs, mend tools, & case harden, &c.
So it may be the case that in the gunlock factories the workers were working with/finishing imported lock parts--though it is hard to imagine how these imports would have persisted in 1776 and 1777 and 1778 and 1779 etc.
After 1777, the newly organized/consolidated continental commissary for military stores spent a lot of effort providing steel to its various factories (see Robert F. Smith, Manufacturing Independence: Industrial Innovation in the American Revolution [2016], which tells the history of the creation, after much chaos in 1775 and 1776, of the high-functioning Department of the Commissary General of Military Stores). In January 1778, for instance, Benjamin Flower took over Andover Furnace in northern New Jersey, whose owners were Loyalists, and used it to provide steel for the workmen at the Carlisle armory.