Howdy, John:
I just pulled this information off the Internet, but I know it's been covered before on other forums. In a nutshell, the Rogers and Spencer wasn't released until after our 1840-1865 time frame.
Best,
Caleb
The Rogers & Spencer Percussion Revolver was originally manufactured in Willowvale, NY about 1863-65. In January 1865, the United States government contracted with Rogers & Spencer for 5,000 of the solid frame pistols. Delivery on the contract was made too late for war service, and the entire lot was sold as scrap to Francis Bannerman and Son in 1901. Bannerman then sold the pistols throughout the first quarter of the 20th Century. Many original Rogers & Spencer revolvers are seen today in excellent, near mint condition.