This was Horace Smith's (later Smith & Wesson) improvement on the Jennings "Rocket Ball" rifle manufactured circa 1851-52. He was issued a patent in 1851 for an improved action and the repeating rifle was manufactured by Robbins & Lawrence. This particular rifle is a Second Model with the pronounced bulge on the underside of the frame resulting in the nickname "pregnant frame Jennings". It is estimated that less than 400 of this model were manufactured. Also the pill primer and cartridge carrier position spring were improved over the First Model. The left side of the receiver is marked "PATENT 1849/C.P. DIXON AGENT/NEW YORK" and has light engraving on the receiver and buttplate tang. A magazine tube is positioned under the barrel. Small blade front and fixed iron rear sights. The top of the barrel is marked "3B" at the breech. It has the simple swinging loading gate configuration, ring trigger and mounted with a smooth straight grip stock with an engraved silver oval inset on the right side. The Jennings and the Smith-Jennings rifles are important in the evolution of Winchester having brought together the talents of B. Tyler Henry (who later played a major role in the development of the rifle and ammunition for Volcanic, New Haven and Winchester Arms companies), Horace Smith and Daniel Wesson, (later Smith & Wesson) whose efforts ultimately led to historic developments in the lever action repeating firearms. The Jennings and Smith-Jennings rifles have only recently been properly classified by a detailed study in "Evolution of Winchester" by R.B. McDowell.