Courtesy of reader Mike, we have today a copy of a Master’s thesis written by Major John Davis in 2007, as a part of a Staff College degree. The title of the paper is “U.S. Army Rifle and Carbine Adoption Between 1865 and 1900”, and the first two thirds of it comprise a pretty good history of the rifle adoption process at the time. It begins with the Allin conversions of the Springfield (colloquially called the Trapdoor Springfield), and goes through the adoption of the Krag rifles and carbines.
During that time there were several testing boards convened to investigate new rifle designs, including many with magazines. Davis’ thesis covers these series of tests well, and gives some insight into why the Trapdoor remained the official US rifle for so long. Several of the competing designs are pretty interesting guns in their own right, including the Winchester-Hotchkiss, Remington-Lee, Chaffee-Reese, and others.
The final third of the paper left me a bit flat, though. I expect the thesis was required to apply a historical study to a current day military issue, and Davis makes the argument that the rationale for maintaining the Springfield in the face of newer technology is parallel to the rationale for the modern Army not replacing the AR platform.
To this end he discusses the various replacement options like the XM-8 and HK 416, and cites a couple anecdotal cases of M4 carbines malfunctioning in battle (although apparently not arguing with the stated 5000 average rounds between failures for the weapon, which is extremely good).
Whether Davis effectively makes the argument for replacing the M4 I will leave up to you – but his coverage of the 1870 and 1880s trials is excellent, and well worth reading: