The C.S. Pettengill Revolver was an American Civil War era, double action only revolver. Although the mechanism was originally designed by C.S. Pettengill in 1856, the Pettengill Revolver was produced by Rogers, Spencer & Company from 1858 until 1863, for both the US Army and Navy.
The C.S. Pettengill Revolver was originally developed by C.S. Pettengill in the mid 1850s, with a patent issued in 1856 for his double action esque mechanism (which was fully concealed within the frame). The design was further refined after the end of Samuel Colt's US patent over revolving firearms ended in 1857, entering production in 1858. The design was produced by Rogers, Spencer & Company in Willow Dale, New York.
The first few hundred Pettengills were produced for the US Navy, which saw a production run of 900 in total.  After the start of the American Civil War, the US Ordnance Department took an interest in the design, ordering 5,000 in .44 calibre in 1861. However, this contract was reduced to 2,000 after the Pettengill sent to the Ordnance Board for testing failed. These 2,000 were delivered to the US Army by January 1863, ending the production of the Pettengill.
Of the 2,000 Pettengills delivered, 500 were issued to the 3rd Michigan Cavalry, with the rest issued to individual officers and members of the 1st Arkansas regiment, 3rd Illinois regiment, 3rd Kentucky regiment and the 3rd and 5th Missouri Militias. These were all mounted regiments, and could take advantage of the double action design as they wouldn't have to take their hand from the reins to cock the Pettengill for the next shot.
The Pettengill is easily identified by its lack of an external hammer, which is fully concealed within the frame. The hammer is 'L' shaped and operates with a pepperbox-style double action mechanism This was combined with a percussion lock mechanism, which required percussion caps to fire each round, which were placed onto the percussion cones at the end of the cylinder.
The barrel differed in length (and bore) depending upon which version of the Pettengill was ordered. For Navy versions, the barrel measured 4.5in in length, and bored to accept a .34in round. The Army model had a barrel of 7.5in in length and bored for a larger .44 calibre round. The barrel was also given six rifling grooves, regardless of model.
The Pettengill, as mentioned above, was produced in two different calibre sizes. The Navy model fired a round of .34 calibre (which was smaller than other 'Navy' revolvers such as the Whitney Navy Revolver), while the Army model fired a larger .44 calibre round. The rounds were loaded into a six chambered cylinder in paper cartridges, with each chamber having an individual percussion cap mounted onto the rear of the cylinder.
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 http://www.nramuseum.com/the-museum/the-galleries/a-nation-asunder/case-38-arms-for-the-union-union-pistols/c-s-pettengill-navy-model-revolver.aspx
- ↑ 2.0 2.1 2.2 2.3 2.4 Graf, John F., Standard Catalog of Civil War Firearms (Google eBook), (Krause Publications: 2009), p.217
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 Flayderman, Norm, Flayderman's Guide to Antique American Firearms and Their Values, (F+W Media Inc.: 2007), p.367