This very unusual Austrian single shot percussion pistol was rebuilt in Belgium and then appears to have been exported to the US. The lock markings are somewhat mystifying as the typical Austrian 852 (1852) is found at the bottom center along with US slightly forward and below the bolster and a US style 1851 horizontally at the tail. The lock has been altered from flint to percussion. The overall length is approx. 16"". The 8 7/8"" round 67 caliber smooth bore barrel has a fair bore with light roughness. It has the oval Belgian ELG proof at the top rear. The barrel tang appears to have numbers but they are indistinct. All metal has a smooth light brown patina. The brass ramrod thimble, trigger guard, and butt cap are very good with an nice age patina. The ramrod is not present. The stock is fair with a missing chip at the left front at the barrel and a 1.75"" by .25"" triangular chip at the left barrel-tang intersection. The butt cap has a top and bottom screw with a third open hole centered between them tat leads to a cavity in the lower grip. The purpose of this is unknown to us. The action functions correctly. The lock markings of US and 1851 appear to be from the period and genuine to us and another well-known Civil War expert. However, we don't know their origin or what they signify. This interesting pistol certainly merits further research.