just a little information on Perkin, many of the members of this Forum may already know.
There is quite a bit of info on Perkin (not Perkins) in Harpers Ferry Armory and the New Technology by Merritt Roe Smith, 1977 and a whole book, Harpers Ferry Arsenal & Joseph Perkin by Rick Hudak and Stuart E. Brown. 2012, about Perkin.
Perkin worked for John Strode, manager of Rappahannock Forge, who " Recognizing Perkin's ability as a "useful ingenious man", Strode "kept him chiefly at Gunlocks", a task assigned only to the most skilled artisan." Harpers Ferry and the New Technology , Merritt Roe Smith, page 38.