The B-Type:

MIL-W-46374B Specification

the Generic Military Field Watch

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Copyright 2002-2005 by E C Frederick
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Hamilton W-46374B
Timex W-46374B

MIL-W-46374B, published 7 May 1975, added the requirement for the H3 and radiation symbol to the dial, "centrally located and clearly visible". Revision B also broadened and deepened the requirements for handling, applying, and disposing of Tritium, and watches containing Tritium. These "B" type watches were the first required to have "Dispose Rad. Waste" inscribed on the caseback. Also new was the requirement for a durable protective clear coating on the hands. This explains why the tritium luminous material on the "B" type watches seems to stay adhered to the hands much longer than on earlier versions. The watch strap (specified as a Type II MIL-S-46383B strap) was to be Olive Drab in color. As with earlier specifications in this series, the bars were required to be fixed or "integral". Spring bars are specifically excluded.

This exclusion of spring bars is interesting, because so many "B" type watches being resold now have spring bars. It seem that the real deal should have fixed bars! Obviously the fixed bars have been replaced over time. The MIL-W-46374B example shown above has fixed bars, or the plastic Timex version has integral bars.

Although plastic-cased watches were covered under this spec, only the rare and exotic Timex MIL-W-46374B shown on the right above was made and in relatively small number. Instead the specified "corrosion resistant steel" option was the case material of choice for most "B" issue watches.


The caseback markings on the MIL-W-46374B watches followed the specified eight line pattern shown below. Following this listing, we will describe what each inscription means in a bit more detail.

Caseback Markings US-Issue MIL-W-46374B Hamilton

Line 1: Description
Line 2: Specification MIL-W-46374B
Line 3: Maker HAMILTON
Line 4: NSN 6645-00-952-3767
Line 4: Part No. MFG. PART NO. 39988
Line 5: Order No. DLA 400 82 C 4845
Line 6: Date AUG 1982
Line 8: Country U.S.

The Description, Specification, and Maker inscriptions should be self-explanatory, but the NSN needs some elaboration.

Most, but not all, MIL-W-46374 issue watches have an important 11 or 13 number code inscribed on the caseback of the watch (e.g., 6645-00-952-3767). This is known as the "FSN" (Federal Stock No.) on older watches or the "NSN" from 1975 until the present.

This code begins with the four-digit FSC (Federal Supply Classification) code 6645 that designates "Time Measuring Instruments". Every watch issued since the 1950’s, as well as stop watches, clocks, timers, etc., carries this designation incorporated into its NSN.

The National Stock Number (NSN), has a two number "country code" following the FSC "6645" on the National Stock Number (NSN). So a newer (1975 and later) NSN would read, "6645-00-952-3767", but an older FSN for a similar watch would read, "6645-952-3767". This two-digit country code is formally known as the NATO code for the National Codification Bureau (NCB). All US issues have either a 00 or 01 country code in this spot. Examples of other country codes that might appear on military issue watches are: 21 for Canada, or, 99 for the UK.

The final set of seven numbers called the National Item Identification Number (NIIN), designates the specific item. This is similar to what is known as an SKU (Stock Keeping Unit) in the civilian retail world. The NIIN designates a particular item usually required to be made under a specific military specification (although not always) and adding specific requirements of its own. For example, the NIIN 066-4279 designates watches made under various specifications but limited to watches that hack and have a high quality movement with 15 jewels or more.

The NSN and FSN are important to collectors of issue watches because they provide more specific information about the quality of the watch in question than the mil spec alone.

Most Common NSN:

The common NSN 6645-00-952-3767 designates non-hacking 7 jewel general purpose watches like the common MIL-W-46374B Hamilton, SandY 184, or newer Marathon Model 359 issue (1997). Although this NSN designates the lowest common denominator in military field watches, it is also found on some of the most collectable watches in the MIL-W--46374 range. For example, the Benrus MIL-W-46374 Plastic "non-maintainable" 1966 issue (which is one of the first MIL-W-46374 issue watches); the rock-solid, SandY 184 and 184A; and the current Marathon MIL-W-46374F Type 2 mechanical general purpose watch. This NSN (or FSN) has been used for over 30 years.

Manufacturer’s Part Number

This code designates the manufacturer’s item number. The MFG. PART NO. can provide useful and significant information. For example, watches carrying the same part number can be issued under different specs and carry different NSN’s even though they are identical in case, dial, hands, and movement. The best examples of this are watches carrying the MFG. PART NO. 39986. This part number is used by Hamilton on their higher quality field watches. It seems to indicate (I have yet to see an exception to this) the use of the ETA 2750 movement – a good quality 17 jewel hacking movement. Some 1988 W-46374D issue watches have this desirable MFG PART NO., and some Hamilton mil spec GG-W-113 watches have this same movement. Even thought these watches are made under different specifications, they have nearly identical dials, hands and cases, as well as the exact same movement. The only apparent difference is that some (but not all) W-46374D examples have the H3 and radiation symbol on the dial, whereas the GG-W-113 versions eschew that dial clutter in favor or greater legibility. Exceptions to this observation have been reported by watch expert Ronald Harrison who has seen MIL-W-46374D Hamilton watches without the H3 (tritium mark) and radiation symbol on the dial.

Read that number carefully. For example, the similar designation MFG. PART NO. 39988 on Hamilton watches (including all "B" types I have seen or read about) is an indication that there is a cheaper 7 jewel non-hacking movement under the hood. There is quite a range in the quality and reliability of the various movements found in MFG. PART NO. 39988 watches.

According to Greg Leveto’s informative web site on Hamilton watches (Hamilton Military Watches) and a close look at the photos of W-46374B examples shown in Whitney’s, Military Timepieces. The MIL-W-46374B watches made with this part number can contain one of many different movements (e.g., 447 Grade; 466 Grade; and so on). Most are not Swiss made and although you can find the occasional MIL-W-46374B watch that keeps time to within 10 seconds per day, most fall well outside that range unless they have been maintained and professionally regulated. By the way, the specification only calls for ± 60 seconds per day accuracy under normal conditions.

Order Numbers

The U.S. Department of Defense attaches an order number to awards for the purchase of watches for the military. In most cases that order number, technically known as the Contract Award, will be inscribed on the back of the watch. More recently the order numbers look something like this: DLA 400 82 C 4845.

You can sometimes learn one useful tidbit from this code and that is the year that the order was issued. In the case of the above example, the order was placed in 1982 (note the "82" to the left of the letter code, "C". Using this order number you can also search DoD records, if you have access to the right databases, for details on this specific order. It is possible in the case of relatively recent order to find our how much was paid for these watches and what quantities were ordered.

Date Confusion:

Often erroneously called the "Issue Date" the month and year inscribed on the back of many W-46374 watches tells you either when the watch was made, the date of the contract award, or its date of "acceptance" by the DoD. This creates inconsistency and uncertainty regarding the exact meaning of the date found on the back of many MIL-W-46374 issue watches. Generally people mistakenly assume that this is the issue date, the date the watch was distributed to end users or supply units, but that is never the case, at least with MIL-W-46374 watches.

In some cases, a particular order, NSN, or specific specification might require that the date be the date of assembly of the watch. In other cases, it indicates the date the contract for purchase was awarded (award date), or it can refer to the date the watches were accepted (read "approved") by the DoD.

In no case was I able to find any indication that the inscribed date indicated the date the watch was "issued". Some collectors maintain that "issue date" corresponds to the date the watch becomes government property, but others use this to mean the date the watch was distributed to the people who actually use it. There is no way to know from the inscriptions on the back of a watch when, or even if, a particular watch was given to an individual for their use.

In most cases, the inscription tells us when the watch was assembled. If that's your definition of "issue" then this would be the information you are looking for. Date of Manufacture means the date the watch was put together or assembled. Date of Acceptance means the date the watch model passed its qualifications and was accepted by the DoD. Date of Award means the date that the DoD placed the contract award with the manufacturer. All MIL-W-46374B watches are inscribed with the date of manufacture or assembly.


The Hamilton steel-cased version was issued in the late 1970's (first I've seen has a date of manufacture of Jan 1977) until the mid-1980's ( I believe AUG 1983 is the last date), and they are perhaps the most commonly available military watches. I estimate, for example, that over 120 are offered on eBay alone each year. Hamilton MIL-W-46374B watches in Very Good or Excellent condition command $90 and up. The record auction bid in recent years for an Excellent condition MIL-W-46374B Hamilton was $280 on German eBay. Several in Mint or Excellent condition have topped $200 over the last 18 months. There is clearly a wide range of perceptions of the value of this common mil watch.

Ironically, the most rare and exotic of all MIL-W-46374 issue watches is the Timex issue. This plastic-cased watch, very similar in appearance to the earlier Benrus plastic-cased issues, originally thought to only have been manufactured in February 1982, was also issued in March 1982. Many thousands must have been issued, but only a handful appear to have survived. I estimate about 1 per year appear at auction and i have only seen one with the Mar 82 date in the last seven years. This watch is made even more interesting because it is most likely the only Timex military issue watch made under a military specification. Other Timex watches have been purchased by the military and issued, but they have not been made to a military specification. This combination of basic scarcity and the simple fact of being the sole Timex mil-spec watch puts this watch's value into the realm of the unknown and, just possibly, into the stratosphere for a serious collector.

For more pictures and detail on this rare Timex, see Allan N's special page on the Timex MIL-W-46374B.

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