Military Submariner · Caseback Reference
Military Submariner
Caseback Codes in Detail
Military Submariner caseback detail
“This subject would deserve a medium size book, however I think it is interesting to share some basic information particularly referring to military watches delivered to UK Forces from the 50s on. In the short space of a single work it is impossible to describe all possible situations and every peculiar chance — so all owners of eventual ‘exceptions’ are kindly requested to share them.”
WW II & Earlier Engravings
During the WW II and sometimes up to the 2nd half of the 1950s, the most common assignation formats were as follows:
1. British Army
(Note: after Cromwell the British Army is not “Royal” — that term is granted only to single units distinguished by bravery or loyalty.)
- WWW (= Waterproof Wrist Watch) followed by a capital letter identifying the manufacturer — K for Timor, Y for Omega, F for Longines
- The broad arrow — a stylized arrow pin identifying the item as Crown property
- One or two series of digits showing the progressive delivery number and sometimes the watch case number
broad arrow
WWW
K
8211 (delivery number)
36791 (case number)
WWW
K
8211 (delivery number)
36791 (case number)
2. Royal Air Force
- Broad arrow
- Abbreviation 6B (sometimes 6BB, 6A, or 6E) followed by a number (usually 3 digits) identifying the particular model and type
- Year of delivery and progressive assignment number
- In WW II watches, sometimes also the abbreviation AM (= Air Ministry)
Regarding delivery numbers — it is critically important to emphasize that every new year the assignment number did not restart from “1” but continued from the very first free number. If in 1945 the last number assigned was “6431,” in 1946 the first watch received “6432.” This procedure was followed by all UK Forces.
broad arrow (often absent if “AM” present)
AM
6B/159
10233/40
AM
6B/159
10233/40
3. Royal Navy (includes Royal Marines & Fleet Air Army)
- Broad arrow
- HS (= Hydrographic Service) — used also for R. Marines and other Navy branches, followed by a number (1–11) defining type and/or destination. HS 9 = wrist chronograph; HS 10 = diver’s watch (CD = Clearance Diver)
- Progressive assignment number and/or case number
broad arrow
HS 10 CD (Clearance Diver)
942.115
Example: Military Rolex Explorer ref. 6150
HS 10 CD (Clearance Diver)
942.115
Example: Military Rolex Explorer ref. 6150
Hybrid Engravings
Since the beginning of the 1950s, backs appear with series of numbers often wrongly attributed to the NATO Stock Number code. Two key UK military codes were assigned by the Ministry of Defence:
Code
0552
Assigned To
Royal Navy watches
Code
W10
Assigned To
British Army watches
These are defined as “hybrids” as they contain elements of both national classification and NATO classification systems.
Example I — Omega “Fat Arrow” (RAF)
6645-101000
6B-542
6850/53
6B-542
6850/53
- 6645 = NATO code for a wrist watch
- 101000 = 6-digit number identifying the model (later expanded to 7 digits)
- 6B = RAF
- 542 = MOD type code for a pilot wrist watch
- Progressive delivery number
Example II — RN Hamilton Chronograph
0552/924-3306
1720/72
1720/72
- 0552 = R. Navy watch
- 924-3306 = model + type code
- Progressive delivery number
Example III — Same Model Delivered to RAF
6BB-551
1860/72
1860/72
- 6BB (or 6B) = RAF
- 551 = type code used by RAF for this model
- Progressive delivery number
Note: sometimes the 7-digit type code remains unchanged in the NATO Stock Number (as for Rolex milsubs); sometimes it changes, as shown in the NSN section below.
NATO Stock Number (NSN)
The NSN system arrived around the mid-1960s. It was designed to enable perfect identification within NATO of every kind of supply — from bullets to spare parts for laundry machines — allowing easy classification and procurement of all items in use or expected to be used in the military environment.
The NSN consists of 13 digits in three segments:
Segment A — Digits 1–4
Species (sort) code — defines “the family.” 5305 = screws; 6645 = wrist watches
Segment B — Digits 5–6
Country code of the nation assigning the NSN — may differ from country of manufacture
Segment C — Digits 7–13
Own item code — 7 digits with “no inherent significance” (completely at random, progressive by time of codification). A 7-digit code can be shared by more than one country (as for watches), or used by only the originating country.
Country Codes
00–09 · United States
99 · United Kingdom
12 · Germany
14 · France
15 · Italy
UK NSN Examples
British Army — Smith watch, delivered 1970
W10-6645-99-961-4045
1579/70
1579/70
British Army — Omega SM 300 & Rolex Mil-Sub (shared NSN)
W10-6645-99-923-7697
288/67 (example: Seamaster)
288/67 (example: Seamaster)
Royal Navy — Rolex 5513 (hybrid format, not full NSN)
0552-923-7697
199/74
199/74
Royal Navy — Omega SM 300 (hybrid format)
0552-923-7697
577-70
577-70
Footnote: Up to the present day there is no proof that progressive delivery numbers could start every year from a number lower than the highest one assigned in the previous year.