1930s Rolex 2303 28.5mm monopusher chrono - info?

[/16610]

Very niche, I know…

but does anyone have any info on this c.1930s chronograph?


Here’s the Collector Square page on it with the auction listings I've used and pretty pictures in case you’re not familiar: https://www.collectorsquare.com/en/w...rolex-2303/lpi



So far I have:


28.5mm ‘boys size’ case, in steel or 18k yellow gold

10.5 ligne chronograph movement, running seconds, 30 min counter, monopusher

Advertised as smallest chronograph in the world

Price in an as of yet unknown date Italian advert: 1000 lire for the steel, 1925 lire for the gold


'Ordinary dials': Silvered sector dials on both steel and 18k YG observed in advert and auctions, black non sector dials on 18k YG pieces observed at auctions

All watches have tachymeters

Blued feuille hands unless black dial, in which case white feuille hands


Four 'unique' dials:

'Kerney' retailer signed dial (Antiquorum sale #295, 18k YG, black non-sector dial, case no. 16,121)

'Broudarge Paris' retailer signed dial (Christies sale #1357, 18k YG, silvered and white two-tone dial, arabic numerals, case no.17,887)

'Breguet numerals' (Christies sale #2168, 18k YG, silvered and white two-tone dial, case no.14,743)

'Ronchi Milano' retailer signed dial (Antiquorum sale #108, 18k YG, silvered sector dial, case no.17,890)



Age range claimed in auction descriptions: 1928-1935… however some of the case numbers seem to be pre-1927 (the Dowling case number chart doesn’t reach back past 1927)…

Case numbers observed in auction catalogues range from: 16,121 -> 22,310... according to Dowling table, that's pre-1927, 1927, and 1928.)






So, ideally:

1. As precise as can be had production timeframe

2. Who actually made the movement? Was it in other stuff?

3. Can anyone think of a smaller (mechanical?) chronograph since then?