Hi Bryce - I'm aware of the following on microfilm (Nat. Archives M1281) : "Summary statements of quarterly returns of ordnance and ordnance stores on hand in regular and volunteer army organizations 1862-1867, 1870-1876." It's on several microfilm reels, and I currently have reel 1 (artillery), and reels 2-3 (cavalry) checked out and am going through them (only for selected regiments I'm interested in). It is very tedious work! (the films are rather faint).

The book I mentioned (McAulay's "Carbines of the U.S. Cavalry 1861-1905" MAY have used these films, but I get the sense that perhaps he used more specific quarterly statements from RG 156 (Records of the Chief of Ordnance) that may exist in the Nat. Archives. Regardless, the book is a useful first reference work, though it only gives carbine summaries for Dec. 1862, Sept. 1863, and "Summer and fall" 1864, and honestly I'd use the info with a little healthy skepticism. Much easier than the microfilm!

John