With only a few hundred made in 1851, the common version is the 6-shot 4" barrel.  Examples of 5" 5 shot models would be considered very , very rare. Mfg in Springfield Mass with two piece high gloss varnished stocks and blued finish. This gun shows all the cylinder scene. Perfect mechanics. perfect nipples. Finish is basically patina, smooth with no pitting.  Chances are you will never see another example like this.  Very rare low production pre Civil War pocket pistol. gem mint bore.