I don't know if someone else has found the answer to the question Norm Flayderman mentioned in my older (2nd) edition of "Flayderman's Guide" or not. Specifically, writing of the Ellis repeating flintlock rifles, he states "It is not known how many of the 520 pieces [the number contracted for] were actually delivered..."
I stumbled across this information while doing some research on a cannon. Near the bottom of the page shown below, is an entry apparently dated 19 October 1829: "521 repeating rifles made by R. Ellis under contract dated 28 April 1828, and delivered to the state..."
Source: Ledger entry dated October 19, 1829, page 7, volume 3, Ledgers and Journals of Ordnance and Ordnance Stores Issued to the Militia (Entry 118,) Records of the Chief of Ordnance (Record Group 156,) National Archives Building, Washington DC.
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