Sharps NM 1863 carbine question

[moleary]

I have an 1863 Sharps carbine with a worn SN and looking for help with dating it. Pix below show what I think is the "C" (100,000) mark in front of the numbers, as well as remnant of another digit at the end. Anyone agree/disagree? It has an iron patch box and I can't find anywhere if the patch boxes were an option throughout the NM1863 production range, or only at the beginning before they were removed? Any thoughts welcome!

[Patrick Chadwick]

Sources:
"Sharps Firearms" - Frank Sellers.
P.84 shows a New Model 1863 Carbine. Serial No. C29105. No patchbox. But no info on a changeover date.

"Civil War Sharps Carbines & Rifles" - Coates & McAulay.
P.49. 2nd Arkansas Cavalry (Company L). Issued with Sharps carbines in Range 21xxx-25xxx. Probably late 1864.
P.82. 15th New York Cavalry (Company C). Issued with Sharps carbines on Feb. 2, 1865 "to replace Burnside carbines". I.e. all at the same time. This is the only entry I have found with a definite issue date. Numbers mostly from C20136 to C23024 (49 pieces). Below that number range there are recorded: C2238, C4668 (probably already in service) and C's 19045, 19078, 19105, 19358, 20136, 20551, 20997.

The numbers C19045-20997 may represent factory stock that just happened to be issued with the new 21xxx-23xxx batch.
Other units also received carbines in these number ranges, but there is no discernable pattern. Sharps just seems to have picked them out of the pile and shipped without any regard to number sequence.

Conclusion: your carbine was probably manufactured late 1864.
As to the patchbox question: I have not found a definite changeover date.