Correspondence and legal papers relating to Maynard's invention of a percussion primer (known as the Maynard tape primer), his patent of it in 1845, and his efforts, plus those of his partners, Thomas L. Smith and J. Washington Tyson, to get firearms manufactured utilizing the primer. Some correspondence relates to his improvements in the breech-loading rifle and the sale of his patent rights. Correspondents include Timothy W. Carter (agent of the Massachusetts Arms Company), George Mackay, Edward Riddle, Thomas L. Smith, and Joseph Washington Tyson. Also included are account books documenting Maynard's Washington, D.C., dental practice. Patients mentioned include Samuel Cooper, W. W. Corcoran, John A. B. Dahlgren, Stephen Arnold Douglas, Thomas Ewing, Philip Kearny, Horace Mann, George B. McClellan, George Washington Riggs, Edwin McMasters Stanton, and Joseph Vann.