Only a small number of the Jennings rifles were manufactured by Robbins and Lawrence in 1848-1852. The Jennings rifles mark the important second step in the evolution of what eventually became the Volcanic, Henry, and Winchester lever actions. Work on the Jennings rifles at Robbins and Lawrence is credited with bringing together B. Tyler Henry, Horace Smith, and Daniel Wesson under the same roof and thus helped lead to what became both the highly successful Winchester lever action series and the iconic Smith & Wesson partnership. Beginning in 1852, Robbins and Lawrence abandoned the underpowered rocket ball cartridge in favor of building muzzle loading variants. Many of the original breech loaders were altered by outside gunsmiths into muzzle loaders as well. It still has the round pill primer on top and a rectangular loading cut out. The ring trigger that originally pushed the breechblock into place and operated the automatic pill primer on the breech loading versions now functions simply as a trigger for the hammer. The only visible markings are "WINDSOR VT." on the left side of the receiver, "465" on the lower tang, and a scroll engraving on the receiver and buttplate. It has fixed blade and notch sights, a smooth straight wrist stock, and a rifle buttplate.