Originally manufactured by Colt as a Model 1921 Thompson SMG, one of a number stuck in inventory due to sluggish sales; while today the Thompson is recognized as an American classic and one of the all-time finest "heavy metal" SMGs, at the time it was a novel, untested and expensive weapon, and few were willing to roll the dice. The U.S. Marine Corps was an early adopter, and the firm attempted to capitalize on the connection by adding "U.S. NAVY" markings to their 1921s, updating the features based on USMC feedback, and overstamping the "1921" to "1928" to match their newer model. According to Herigstad's "Colt Thompson Submachine Gun Serial Numbers and Histories" (page 1075), this particular Thompson was shipped to the San Benito County Sheriff's Office in Hollister, California, at an unlisted date. The exact usage the Sheriff put this Thompson to is unknown. Blade front sight on the Cutts compensator and a folding Lyman rear sight, showing the signature cooling fins on the barrel, dual hardwood pistol grips, and a quick-detachable hardwood buttstock. The left side of the receiver has the aforementioned "U.S. NAVY" model markings ahead of the 5-line address and caliber markings, with the Thompson "bullet" logo on top and the Auto-Ordnance address and 6-line patent markings on the right. The trigger group is numbered to match the receiver on the underside, with separate selector ("FULL/AUTO" and "SINGLE") and safety ("FIRE" and "SAFE") levers. A purple velvet lined black leatherette American Trunk & Case "FBI" case is included, which holds the SMG, a brass cleaning rod, four blued "stick" magazines, an Auto-Ordnance "L" type 50-round drum, and a San Benito County Sheriff's Department patch.

Excellent, with 97% plus of the bright original blue finish, showing some light edge wear and handling marks overall, and some light retraction wear on top of the receiver around the breech and cocking handle channel. The stock is also excellent, with some light dings and scratches. The accessories are in fine order, and the case shows mild exterior wear and tear overall as well as a loose handle. Mechanically excellent. NOTE: This weapon is a National Firearms Act (NFA), fully transferable Class 3, which is registered with the Bureau of Alcohol, Tobacco, Firearms and Explosives, (BATFE) that is classified as a "Curios or Relic" as defined in 27 CFR, 478.11. These weapons are still subject to the provisions of 18 U.S.C. Chapter 44 and 27 CFR part 478.