This is an antique black powder frame Colt Single Action Army Revolver that letters in .450 Boxer, a desirable caliber that has bemused Colt collectors for decades. In "The Official Record of the Colt Single Action Army Revolver 1872-1895" on page 46 the authors write, “An interesting fact became evident when comparing listings in the Colt ledgers with copies of the actual invoices found in the Connecticut State Library. The designation ‘Eley’ or ‘Boxer’ was used interchangeably. Revolvers listed in .45 Eley in the record ledger may be listed on the shipping invoice as .45 Boxer and vice versa.” The authors accounted for a total of 3,385 Peacemakers in .450 Boxer falling in the 1-164100 serial number range and out of the 3,385 units only 610 had a blue finish and 7 1/2 inch barrel like this example. The accompanying factory letter confirms the .450 Boxer chambering and blue finish and has the barrel and type of stocks not listed, a common indication of a 7 1/2 inch barrel and walnut stocks as these were considered standard features at the time and not usually noted. The letter also states the revolver was shipped to Colt's London Agency, London, England, on March 30, 1874. This was a 50 gun shipment. The barrel has the one-line Hartford address on top, and the left side of the frame has the two-line patent dates marking. London proof marks appear behind each cylinder flute and on the bottom of the barrel at the breech. "45 CAL" is stamped on the left side of the trigger guard. Matching full serial number appears on the frame, trigger guard, back strap, barrel, and cylinder. This SAA is pictured and identified in "The Official Record of the Colt Single Action Army Revolver 1872-1895" on page 372. Single Action Army Revolvers chambered in .450 Boxer were sold throughout the British Empire. These early production Single Action Army Revolvers with British proof marks are scarce. Provenance: The Jonathan Peck Collection; The Richard Atkinson Collection; Property of a Gentleman