Military Submariner Caseback Codes in Detail

Military Caseback Details by Marcello Pisani  


"this subject would deserve a medium size book, however I thinks that is interesting to share some basics informations particularly referring to military watches delivered to UK Forces from the 50s on. 

In the short space of a single work it's impossible to describe all possible situations and every peculiar chances .. so all owners of eventual " exceptions " are kindly requested to share them.

WW II and earlier engravings
During the WW II and sometimes up to the 2nd half of the 50s the most common assignations were the followings : 

1) British Army ( that after Cromwell is not anymore " Royal ", a term granted only to single units distinguished by bravery or loyalty ) :
--WWW (=Waterproof Wrist Watch ) followed by a capital letter identifing the manufacturer ( for ex. K for Timor , Y for Omega and F for Longines ) ; sometimes also the manufacturer name was engraved on the back ;
-- the broad arrow ( a stylized arrow pin that identifies the item as Crown property ) ;
-- one or two series of digits that show the progressive delivery number and sometimes also the watch case number.
so for ex. a Timor watch could have this engraving :
broad arrow
8211 ( delivery number )
36791 ( case number ).

2) Royal Air Force :
-- broad arrow
-- abbreviation 6B ( sometimes 6BB or 6A or 6E ) followed by a number ( usually 3 digits ) identifying that particular model and his type ;
-- year of delivery and progressive assignement number ;
-- sometimes in watches delivered during the WW II there was also the abbreviation " AM " (=Air Ministry ) ;
so for ex. a Longines could have these engravings :
broad arrow ( often not present if there is " AM " )
About the point of delivery numbers is really important to enphasize that every new year the assignement number was not beginning again with " 1 " ( or " 01 " or " 001 " or .... ) but with the very first free number ... so for ex. if in 1945 the last number assigned had been " 6431 ", in 1946 the first watch would get the number " 6432 " .
This procedure was obviously followed by all UK Forces.

3) Royal Navy ( that includes also Royal Marines and Fleet Air Army ) :
-- broad arrow ;
-- HS (= that stands for Hydrographic Service ) , used also for other branches belonging to the Navy such as R.Marines,
followed by a number ( from 1 to 11 ) defining type and/or destination ;
for ex. HS 9 defines a wrist-chronograph and HS 10 a divers watch ;
-- progressive assignement number and/or case number .
so for ex. a military Rolex Explorer ref. 6150 could have :
broad arrow
HS 10 CD ( Clearance Diver )

Hybrid engravings
Since the beginning of the 50s we find backs with series of numbers often wrongly related to Nato Stock Number code :
a) " 0552 " that is a UK military code choosen by the Ministry Of Defence ( and not a " NATO prefix for UK Navy watches " ) for watches delivered to the Navy ;
b) " W10 " : that is another MOD code for British Army watches ;
these codes can be defined " hybrids " as they contain either parts of national classification ( such as " W10 " ) and parts of the NATO one.
Some typical examples :
I) Omega " fat arrow " , with these back engravings :
-- " 6645 " (=NATO code for a wrist watch , a number we shall also find in the Nato Stock Number ) ;
-- broad arrow ;
-- " 101000 " : a 6 digit nunber that indentifies the particular model ( later this number will have 7 digits ) ;
-- 6B ( RAF )
-- 542 , a MOD number that shows the type , in this case a pilot wrist watch ;
-- progressive delivery number ;
so the complete code would be :

2) for a RN Hamilton chronograph we should have :
-- broad arrow ;
-- 0552 ( R.Navy watch )
-- 924-3306 ( model + type code )
-- progressive delivery number ;
so that the complete code would be :

3) in the same model described above but delivered to RAF we should have seen :
--6B ( or 6BB )
-- 551 that is the type code used for this model by RAF :
-- progressive delivery number ;
so that the complete code would be :

NOTE : sometimes the 7 digit type code will remain unchanged in the Nato Stock Number ( as for Rolex milsubs ) , sometimes will change as we will see .

Nato Stock Number
NSN arrives around the middle of the 60s : it was studied to make a perfect identification within NATO of every kind of supplies ( from bullets to spare parts for laundry machines) , in order to have an easy classification and supply of all items already in use or expected to be used in the military environment.
It consists of 13 digits so defined :

A) the first 4 digits define the SPECIES (=sort ) code ; in other words they define " the family " to which belongs the item , so for ex. 5305= screws , 6645= wrist watches ;

B) digits 5 and 6 are the code of the country who has given this NSN , that can be different from the country who has made the item ; so for ex. a watch produced in France can have the country code of another nation , such as Germany or USA .
Some country codes are :
-- from 00 to 09 : United States
-- 99 : UK
-- 12 : Germany
-- 14 : France
-- 15 : Italy

C) the last 7 digits are the own item code : so all 7 digits codes describe an item ( or a group of items with extremely close features ) within the nation that has requested this particular NSN.
This means :
1) the 7 digits code is defined as " with no inherent significance " , so it doesn't give any evident information about the item
( in other words it's completely at random ) ;
2) it's progressive and depends on the time in which the codification has been requested ; for ex. " 545.7078 " can be a lamp and the following number ( " 545-7079 " ) a ground-air missile.
3) some 7 digits codes have been used by more than a country ( as for watches ) some only by the country who has created that code.

Some UK examples :
*) a British Army Smith watch delivered in 1970 had this NSN : 6645-99-961-4045
and the complete delivery code would be :

) Omega SM 300 and Rolex milsubs delivered to the British Army had the same NSN :
so for ex. the complete code for a Seamaster would be :

*** ) Omega SM 300 and Rolex milsubs delivered to the R.Navy still had an hybrid code and not a NSN number
so for ex.
--- a Rolex 5513 had this code :
-- an Omega SM 300 the following one :

FOOTNOTE : Up to the present days there is no proof that progressive delivery numbers could start every year from a number lower than the higher one given in the previous year. 

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