The "knuckle" is truly not a necessary complication of a try gun design. A.P. Curtis designed a try stock while he was employed at a gun company, probably L.C. Smith. It was used by Parker, Ithaca, L.C. Smith, Lefever and probably others. It did not utilize the complicated knuckle yet was adjustable in all directions. My Curtis try gun was made in 1915 if I remember correctly, and it still in use today.