A model 1873 could be a carbine, rifle, or musket. Easy to distinquish these by the barrel length, 20, 24, or 30 inches. There were three models of each. First models will have a serial number under 30,000, second models from 31,000 to 90,000, and third models over 90,000. These ranges are approximate, so if your serial number is close, say +/- 10000, to one of the breaks, it may belong on the other side. You can get a copy of Flayderman's Guide to Antique American Firearms to determine which model you have. This book will also give you an idea of how to grade the condition of the gun and determine the value.
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