I'm looking for some help regarding a marking found on the cylinder of my colt 1860 army. The gun is a recent aquisition for me. It's an original 1860 which shows all signs of being refurbished ("cleaned and repaired") by an arsenel post civil war. The gun is not marked with the "US" found on some of the post civil war refurbished guns but has every other characteristic of these guns as described in Pates book. The mark in question is a "5" on the face of the cylinder (see photo). I haven't seen this mark on any other colt and see no reference to markings like this in Pate's book. The gun has 3 different serial numbers (all dating to 1862 or 1863). The serial number on the cylinder is too faint to read (common on the refurbished guns). The cylinder is definitely of the correct vintage and has a patina consistant with the rest of the gun. Any help identifying this marking would be appreciated.