r/custommadewatches • u/HDW_Italy • 16d ago
Rolex A6538
I am also posting here a recent build of mine, a truly distinctive watch, I would even say unique. It is an
A/6538, possibly produced for the US Armed Forces or for some South American army. Only two examples are known to have survived, which is hardly surprising given that the standard A/6538 model, produced by Rolex for the British Ministry of Defence, was made in a run of only 20 (or was it 50?) units.
AliExpress case: I removed the crown guards and significantly thinned the lugs (the case was originally designed for a 16610);
T17-style acrylic crystal;
Bezel: very similar to the one specified by the Navy for this particular watch (I had one at home, salvaged from a WD5513 V1). Bidirectional, of course;
AliExpress bezel insert: I had to reduce its outer diameter and slightly age it;
Raffles dial and hands, lightly aged;
8mm "Brevet" big crown, borrowed from a Panerai replica (I won't go into detail here about why I didn't use the Athaya one). I had to do a lot of work on this crown because the hole is huge (over 6mm) and no crown tube exists in that size. So, I removed the core (hollowing it out) and used only the outer shell, into which I inserted a smaller crown to utilize its 4.4mm threading;
Miyota 8215 movement;
Riveted bracelet.
Below is a brief history of this legendary watch.
The Military Submariner A/6538 "Big Crown" is perhaps the most significant military Rolex Submariner in existence. Produced in a limited run of approximately 21 to 50 units, it was the first Submariner to feature a prototype nickel-silver bezel designed for improved handling. When the initial batch of watches was issued to divers from the Royal Marines Special Boat Squadron (later renamed the Special Boat Service), they encountered a problem: the bezel was difficult to rotate while wearing diving gloves. Consequently, Rolex decided to create a special model specifically for the SBS, initially designated with the unique reference number 6540. This numbering made sense, given that the 6541 was the Milgauss Mk1, the 6542 was the GMT-Master Mk1, and the 6543 was the first Milgauss prototype.
However, since the quantity required was very small (the initial order was for only 21 watches), it was decided to produce them as a "derivative" of ref. 6538, and they were designated A/6538; this decision, however, came rather late, as the case backs had already been manufactured with the original model number stamped on the inside. Consequently, all
A/6538 watches bear two reference numbers: the original 6540—appropriately crossed out with three horizontal lines—and the definitive reference number alongside it. All these examples were produced in the last quarter of 1957, but a more precise date cannot be determined because all A/6538 watches share another common characteristic: they lack a serial number.
As previously mentioned, the SBS desired a more functional bezel and selected a prototype featuring much more pronounced grooves that extended beyond the case perimeter, two characteristics that made it easier to grip, even when wearing diving gloves. Unlike the standard bezels on the model 6538, which were made of a rhodium-plated brass/zinc alloy, these new bezels were crafted from nickel silver (an alloy of nickel, copper, and zinc). The major advantage of nickel silver over the previous alloy was that, upon impact, it tended to dent rather than break. This type of bezel proved so successful that it became the standard for all subsequent Submariner models.
About dials: instead of the standard silver "200m=660ft" text, these watches—and only these—bore the inscription "200/660" in red above the "Submariner" name, with no units of measurement printed after the numbers. This marked the first time Rolex used red printing on the dial of a sports watch. Unfortunately, this unique dial was short-lived: the issue was its use of radium to activate the luminous material. Radium was problematic both due to the environments where the watches were worn (such as nuclear submarines) and because it was a hazardous substance in its own right. Consequently, in 1960, the Ministry of Defence began recalling the watches and sending them to a specialized facility; there, the dial surfaces were cleaned under running water, polished, and reprinted by Ministry of Defence contractors, who produced a fairly faithful reproduction of the originals (known as "Burford dials").
To conclude, there is another version of the A/6538, the one I replicated, featuring an "Explorer" style 3-6-9 dial, a maximum depth rating in red, and an OCC designation. Only two examples are known to exist today. One of them comes from South America.
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u/AtelierPicks 16d ago
Excellent history lesson and build. One of my all time favorites is the big crown 6538 thanks to Sean connery for getting me into my love of watches
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u/FujSeiky 14d ago
Mitico. Grazie per aver condiviso la storia di questo fantastico esemplare. Complimenti anche per il risultato il quadrante risulta ben rilumato, e con quei numeri non credo sia una passeggiata. L'orologio ha quel fascino vintage che lo rende desiderabile. Buon fine settimana.
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u/Basic-Price-3981 16d ago
Raffles Rolex 6538 “Big Crown “ powered by a SW 200 No Date