An interesting Panerai Ref. 6152 1 “Luminor Panerai” with crown-protecting device and sought-after Angelus Cal. 240 movement has been listed on Chrono24. The vendor is Meertz World of Time in Munich, Germany.
This type of watches were initially produced by Rolex on specific request of G. Panerai e Figlio in 1955. G. Panerai e Figlio began to modify this Reference in the early 1960s. 8-day Angelus movements with 17 Jewels replaced the Rolex Cal. 618s to avoid damages caused by worn out threads due to daily winding of the Rolex movements with low power reserve.
The iconic crown protecting device, a specific development for the GPF 2/56, was adapted for the Rolex cases. It offered a quick release of crown and stem, while keeping the cases free from water intrusion and protecting the crown effectively against shocks.
Panerai 6152 1 “Luminor Panerai”, case number 124982
> Panerai Luminor Ref. 6152 1 on Chrono24
The watch in question is not new to the market. It was already offered by Antiquorum a few years back on November 13, 2010 in Geneva. According to the Antiquorum database the watch did not sell.
> Antiquorum Lot 462, Panerai 6152 1, case numer 124982
Besides having a sought-after Angelus Cal. 240 movement this watch also bears a highly desiderable military matriculation number. The inscription “SMZ. No. 186” is engraved on the case back. SMZ is an abbreviation for the Italian word “Sommozzatore” (english: Diver) and the number 186 is the highest matriculation number in my database.

Case, dial and hands
The case seems to be in a good condition. There is a little inconsistency with the crown protecting device. The lever does not close properly. This could be an indication that either the lever or the whole device has been replaced a some point.
Most crown-protecting devices bear a stamped numer of 1 to 10. These cases were hand finished by Rolex and there might have been slight irregularities in measurements. To deal with these tolerances, G. Panerai e Figlio probably produced 10 slightly different stem/tube/lever combinations and marked them with the corresponding number for future replacements.

The dial of this watch is ok. The “Luminor Panerai” inscription has the correct width. In the following picture the engravings look like they were not executed very well. The “dancing letters” could be due to bad photography post production by Antiquorum. The shape of the index at 3 matches common Angelus dials perfectly.

The following picture shows an Angelus dial with a slightly different shape of the index at 3. It is one of two known dials with the uncommon word sequence “Luminor Panerai, Marina Militare”. The width of the inscription is uncommonly wide and the engravings are deeper and bolder compared to regular dials. There is also a noticeable difference in patina.

However, let us go back to the watch in question. The hands are obviously the short version. This type of hands can easily be found on Angelus alarm clocks made in the 1950s to 1960s. There are several modified 6152 1s with longer hour and minute hands. It has been reported that on very rare occasions the long hands were also found on Angelus alarm clocks.

There is no clear pattern in my database whether long hands are more common or not. I tend to believe that G. Panerai e Figlio originally supplied these watches with long hands. This, of course, is only my personal opinion.
The matriculation number
Watches supplied to the different units of the Italian Marina Militare were usually engraved with corresponding military matriculation numbers. It is said that this inscriptions were applied by G. Panerai e Figlio on special request of the Italian military.

The present watch bears the inscription “SMZ. No. 186” which identifies it as a watch supplied to military divers of the Marina Militare. SMZ stands for Sommozzatore, the Italian word for diver. The number 186 is the highest matriculation number in my database. The high matriculation number in combination with the very high case number 124982 could lead to the assumption that the present watch could be one of the last watches supplied to the Italian armed forces.

The movement
The movement of this watch is a 8-day Angelus Cal. 240 movement with 17 Jewels. Modified 6152 1 watches usually have Angelus 240 movements with a production stamp either of MAI.61 or JUIN.61 and bridges that are adorned with Côtes de Genève finish (Geneva stripes).
In this specific case the stamp says 12.55. This and the brushed finish of the bridges identifies this movement as the first version of Angelus 240 units produced by Angelus on special request by G. Panerai e Figlio. The first version of movements was intended for the GPF 2/56 and is the prevalent version among the watches made for the Egyptian Navy.

This movement is definitely one of those units specially produced for G. Panerai e Figlio. An interesting detail is the balance cock with Incabloc and simple regulating lever. The balance cock has the Côtes de Genève finish and a Glucydur balance wheel. It is without doubt from a later unit. The first batch with date stamp 12.55 usually have an Incastar micro regulation system.
All movements used in vintage Panerai watches
Another interesting observation is the missing Rolex signature on the inside of the case back. The stamps have been removed.
The Angelus Cal. 240 movement is a pillar construction and is therefore prone to vertical pressure. Little pressure can cause the movement to stop. An Angelus Cal. 240 is also significantly thicker than a Rolex 618. I believe the stamps (material) had to be removed to create the necessary space to guarantee a careless function of the movement.

Thoughts
It is interesting to see such a late watch combined with the earliest version of a “Panerai-Angelus 240” commonly seen in the GPF 2/56. A few questions arise. Was the movement replaced at some point? Why was the Incastar balance cock replaced?
Unfortunately neither the description on Chrono24 nor the old Antiquorum entry from 2010 offer any information about the provenance of this watch.
Thanks for your interest.