One thing I thought interesting: Why with Dickert's name being spelled out on the barrel, would the educated officers, that mentioned "Deckard" rifles, not know the difference in Dickert and Deckard.
Hold on, though! As far as we know,
no educated or uneducated eighteenth century officer
ever used the term "Deckard" rifle!! The first instance the term shows up--as far as we know now--is that 1853
Annals of Tennessee, right?
I would be happy to be corrected by further evidence, but I think you'll find that the first time "Colonel John Sevier" said that the battle of King's Mountain was won by men carrying "short Deckard rifles" was in a book published in the early twentieth century. My sense is that your correspondent has repeated this information from this twentieth-century text as if it was an accurate quotation from an eighteenth-century individual.
There are no eighteenth-century sources that we know of so far that use the term Deckard rifle. (Correct me if I am wrong.) The one that Dr. Whisker referenced turned out, actually, to use the term "dickert rifle."
It is easy to imagine that the stories of "Dickert" rifles being used during the 1780s could have been transformed, when put into print
70 years later, into "Deckard" rifles.
Draper's footnote was only repeating information from earlier texts, including the ones from 1869 and 1853 cited above, both of which suggest that Dickert in Lancaster was the maker of the rifles. (And note that in the very first instance, 1853, who says it is a Lancaster maker, also says that he has the very rifle in his possession: presumably he was reading the barrel?) The 1860 Harper's account proposed an alternate story about a Carolina maker. All of those suggestions come 70 or 80 years after the events described.
I look forward to further developments of this thread!