From George Lovell, principal designer of British small arms into the percussion era, concerning Nock's screwless locks:
"These kind of Locks were manufactured somewhat in the same manner as the French 'Platines Identiques' -- the several parts were made by different artificers in Moulds, Guages, and Tools and fitted together by a separate set of men. They are formed entirely without Screws; all the Pivots being fixed by small pins in the outward Plate and bearings on the inner one, so that the Cock, Hammer, and Sear work quite free upon fixed centres and on the accurate fitting and true perpendicular position of these Centres with reference to the Plate the whole of the improved action of these locks depends.
I entirely agree with General Dalbiac in his opinion of the excellence of their construction, and I do not hesitate to state that they are the best Military Flint Locks that have come under my observation. It is true they give a somewhat cumbrous appearance to the stock, but the principal Bar to their general use is their high Price and the difficulty of procuring workman capable of making them in sufficient numbers to meet the Demands of the Service at large."
(Blackmore - British Military Firearms 1650-1850)
The locks could be completely disassembled with a spring vise and had fewer moving parts in the action, and fewer external holes. Henry Nock simply could not make enough of them to meet military demands and they cost too much.
dave