Only 10,000 of these "Plymouth" rifles were manufactured between 1861 and 1864 by Eli Whitney Jr.'s Whitneyville Armory and Whitney Arms Company under contract with the U.S. Navy based upon the rifles designed by Admiral John A. Dahlgren of the U.S.S. Plymouth. Commanding officer's are known to have requested the Plymouth rifles over even more advanced firearms like the Spencer rifles due to the Model 1861's harder hitting caliber and long range accuracy. Records indicate the O.S.S. purchased a few hundred of these rifles to arm resistance fighters in the Pacific during WWII. This example is dated "1863" at the tail of the lock and has second style small patriotic eagle motif and "U.S./WHITNEY-VILLE" stamped on the lock. The tang is numbered "7180" (technically a bayonet number not the serial number). The barrel has standard proof and inspection marks at the breech. The left barrel flat and stock flat have the "F.CW." markings of inspector Frank C. Warner.