For the 1873 Colt martial collector this is the hardest variation to acquire. It's a J (Johnson) & C (Casey) dual sub-inspected revolver. According to John Kopec & Sterling Fenn in their great book "Colt Cavalry and Artillery Revolvers" there are only 11 of these J & C pistols known to exist. With addition of this pistol the number is now 12. They further state that serial #'s 17403, 17432, 17492, 17586 and 17647 were all issued to the 7th Cavalry.The serial numbers (17638) on this pistol all match with the barrel number (7633) being a obvious factory error. The J sub-inspector is stamped on the back strap flat, trigger guard and cylinder. Where as the barrel exhibits the C sub-inspector.  The cartouche is light on the left grip but still visible. The bore is very good and the action is crisp and smooth. Overall the pistol has acquired a pleasing blue-brown patina with about 5% factory blue in the protected area's. Seeing as there are only 12 of these pistols known it's safe to say that the majority of Colt martial collections don't have one of these rare pistols. 

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