From the web site Merrill, James H., american-firearms.com:  James H Merrill was born in Washington, D.C., in 1816.  In 1840 he started working with his brother William in Baltimore as a gunsmith.  In the 1850s, the company Merrill, Latrobe & Thomas was founded by James H Merrill, the brothers Philip Thomas, Lewin Thomas and Ferdinand C Latrobe.  The name was changed to Merrill, Thomas & Co in 1860 or 1861 when Ferdinand Latrobe left the company.  The first patent on breech loading fire arms was filed August 1 1856.  On March 26, 1861, a patent was filed under the new name of Merrill Patent Fire Arms Manufacturing Company, Baltimore, Maryland.  14,255 Merrill carbines and 770 Merrill rifles as well as five and half million cartridges were purchased by the US Army.  These guns were manufactured at the E. Remington factory in Illion, New York, as Merrill, Latrobe and Thomas did not have sufficient production capacities.  Merrill Patent Fire Arms Manufacturing Company filed for bankruptcy in 1866.

Rollin Davis, US Sword Bayonets 1847 to 1865, p23, states the US Ordnance Department records show a total of 770 Merrill breech loading rifles with brass hilted sword bayonets were purchased from Merrill between April 1862 and November 1863.