i have found a reference to the adjustable lump patent being issued in 1872....my copies of crudington & baker are packed away from my recent move, and i can't put my hands on them, or the whatley & crawford history of w & c scott....so i can't direct you to something more official.
i can tell you that the smaller screw is a keeper for the adjustment screw, which, with its eight indents, allows adjustment of the contact between the barrels and the standing breach....these guns can be brought back on face with a couple of turnscrews.
best regards,
tom
ps: i found a case you might consider - it's already monogramed for you....https://www.ebay.com/itm/305176353998?_trkparms=amclksrc%3DITM%26aid%3D777008%26algo%3DPERSONAL.TOPIC%26ao%3D1%26asc%3D20230811123856%26meid%3D0b1361f9613f4d0a9818e833d55b46eb%26pid%3D101770%26rk%3D1%26rkt%3D1%26itm%3D305176353998%26pmt%3D0%26noa%3D1%26pg%3D4375194%26algv%3DRecentlyViewedItemsV2&_trksid=p4375194.c101770.m146925&_trkparms=parentrq%3Afcd996fc18a0a55f163a0c54ffffe668%7Cpageci%3A072d63b9-6307-11ee-8fac-82b6896dfdf1%7Ciid%3A1%7Cvlpname%3Avlp_homepage
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