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The Encyclopedia of Horology

Pocket watch · Military navigation pocket watch

Hamilton Model 4992B Military G.C.T. Navigation Pocket Watch

Partially verified

This Hamilton Watch Co Model 4992B navigation pocket watch was produced for the United States Government under Contract No. W535ac-28072. According to auction documentation, it features a Keystone base metal case numbered 005783, marked on the case back with military specifications including AN 5740, part number 4992B, and serial AF-42-10744. The black 24-hour dial displays G.C.T. for Greenwich Civil Time, paired with luminous hands and Arabic numerals. The internal manual-wind movement is catalogued as a 22-jewel caliber, serial number 4C16435, adjusted to temperature and six positions.

Front view of Hamilton 4992B military pocket watch displaying 24-hour G.C.T. dial
Front view of Hamilton 4992B military pocket watch displaying 24-hour G.C.T. dial — Sphere Auctions LLC. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
www.liveauctioneers.com
Category
Pocket watch · Military navigation pocket watch
Maker / attribution
Hamilton Watch Co
Reference
4992B
Catalogue / lot identifier
0314
Source-reported date
Not established
Country
United States
Source-reported serial
4C16435

Source-reported attribution and specifications are not independent authentication. A listing does not establish present ownership, current display, availability or permission to reproduce.

Object description

Identity and Provenance

This Hamilton Watch Co. Model 4992B is a navigation pocket watch identified by the movement serial number 4C16435. It was manufactured for the United States Government under Contract No. W535ac-28072.

The timepiece is housed in a Keystone base metal case, serial number 005783. The case back features military specification markings, including the designation AN 5740, part number 4992B, and serial number AF-42-10744. These markings are reported by the source.

Evidence for this section
  • “Hamilton Watch Co Model 4992B”
  • “Contract No. W535ac-28072”
  • “serial number 4C16435”
  • “Keystone base metal case, serial number 005783”
  • “case back marked AN 5740, Mfr's Part No. 4992B, and Serial No. AF-42-10744”

Dial and Exterior Observations

The watch features a black 24-hour military dial marked 'G.C.T.' for Greenwich Civil Time. The dial includes luminous hands and Arabic numerals.

The exterior assembly consists of a coin-edged fluted bezel and a fluted bow surrounding the winding crown.

Evidence for this section
  • “black 24-hour military dial is marked G.C.T. for Greenwich Civil Time with luminous hands and numerals”
  • “Coin-edged fluted bezel and fluted bow around the winding crown”

Mechanical Specifications

The movement is signed by the Hamilton Watch Co. and contains 22 jewels. It is described as being adjusted to temperature and 6 positions.

Seller-reported operational data from a timing machine indicates a rate of minus 2 seconds per day, 329 degrees of amplitude, and 0.0ms beat error. These metrics are not independently verified.

Evidence for this section
  • “movement is signed Hamilton Watch Co USA, 22 jewels, serial number 4C16435, adjusted to temperature and 6 positions”
  • “timing machine reading of minus 2 seconds per day, 329 degrees of amplitude, and 0.0ms beat error”

Open research questions

  • Does the movement serial number 4C16435 fall within the production range assigned to the W535ac-28072 contract?
  • Is there a standardized record reconciling the Keystone case serial number with the military AF-42-10744 serial number?

Source evidence

Recorded claims and source quotations for Hamilton Model 4992B Military G.C.T. Navigation Pocket Watch
FieldSource-reported valueSource quotation
Model4992B“Hamilton Watch Co Model 4992B”
Government ContractContract No. W535ac-28072“Contract No. W535ac-28072”
Movement Serial Number4C16435“serial number 4C16435”
Movement Jewels22 jewels“22 jewels”
Dial MarkingG.C.T.“marked G.C.T. for Greenwich Civil Time”
Case Specification MarkingAN 5740“case back marked AN 5740”
Case ManufacturerKeystone base metal case“Keystone base metal case”
Production claimone of only 40,000 made“one of only 40,000 made”

Visible details

  • Black 24-hour dial with luminous Arabic numerals and an outer minute track calibrated in 5-minute intervals
  • Spade-style luminous hour hand, matching minute hand, and a long center seconds hand with counterbalance
  • Coin-edged fluted bezel and fluted bow around the winding crown
  • Dial text reading 'G.C.T.' centered below the 24-hour index

Research qualifications

  • Movement and case back markings are described in the listing text but not visible in the provided image
  • Operational timing metrics and service claims are source-reported and not independently verifiable

Photograph identity and source facts were screened before import; rights clearance remains pending.

Consulted source

Hamilton 4992b Military Gct 22 Jewel Navigation Pocket Watch - Fully Serviced, Us Government Contrac - Sep 5, 2026 | Sphere Auctions Llc In Wi

Reviewed 2026-10-22 · Record ab78434923

Terms in this record

Glossary explanations for terms named in this object’s record.

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