After Gettysburg in July 1863 27,574 muskets were picked up by the Union from the battlefield, according to the report of Lt. John R. Edie, Acting Chief of Ordnance, Army of the Potomac. This is found in The War of the Rebellion: A Compilation of the Official Records of the Union and Confederate Armies, a/k/a “The ORs.” It is found in Volume XXXIX on “The Gettysburg Campaign”, p. 255. The report is also found in the Congressional Series of United States Public Documents, Volume 2771.
What is interesting is that of those 27,574 musket, most of them—the figure 24,000 is most often used-- -were found loaded and many with more than one round. This is mentioned in more than a few books as a statement of fact, but they generally use another book as their source. Where did this widely accepted figure of 24,000 loaded muskets come from? Do we know what the original source for this amazing statistic might be?
To start with, the statistics on the discarded, loaded muskets picked up by the Union after Gettysburg are usually stated in those suspiciously round numbers. The fantastical claim that one recovered musket had 23 rounds loaded in it is also just accepted as a matter of fact. Try that sometime and you will find it would require a barrel five or six feet long.
The most you will find for backing of these claims is an oblique reference to “Records” or “Reports” or if the passage is cited, another book which references “records or reports” but again provides no original citation. Good reason for it, too... I know of no official record or report that supports that 24,000 is the correct number and as a result it seems debatable. Paddy Griffith in the excellent Battle Tactics of the Civil War (p. 86) is dismissive of those figures as quite likely exaggerated as well.
The earliest mention I can locate for these 24,000 loaded muskets gleaned from the fields of Gettysburg is a West Point text book titled A Course of Instruction on Ordnance and Gunnery for Cadets of the United States Military Academy (1867) by Brevet-Colonel JG Benton, p. 341, where he mentions that:
at least 24,000 were loaded. About half of this number contained two charges each, about a fourth contained from three to ten charges each and the balance one charge. The largest number of cartridges found in any one piece was twenty three. In some cases the paper of the cartridges was unbroken and in others the powder was uppermost.”
As to where the nice round, tidy figure of 24,000 loaded muskets actually came from, who knows? It appears to be completely anecdotal, water cooler talk around the Arsenal so to speak and Colonel Benton is primarily interested in providing these figures to the cadets in his class to make a broader point about the dangers of overloading the barrel of a musket (it may burst). The passage is contained in the textbook as a sub-chapter on the “Durability and Strength of the Musket Barrel.” Colonel Benton does not provide any source for the loaded musket figures from the Arsenal.
If there is an official report or record from the Washington Arsenal that addresses where these figures came from or broke it down further, it is not cited. The soldiers on fatigue duty loading the muskets from the battlefield would not have attempted to check to see if they were loaded or keep any such records on the numbers. It would be within the area of responsibility of the armorers at the Washington Arsenal to receive these arms as they were returned from the battlefield, inspect them, clean them which would include any necessary unloading of loaded barrels and perform any necessary repairs to return them to active service.
However, it’s probably a dead-end beyond that. These are the figures provided by Colonel Benton and stated as a matter of fact from his
textbook for Cadets from his course at West Point in 1867, but if you want primary source backing beyond this level it probably doesn’t exist.