Airain Type 20 Vert Militaire Limited Edition Re-Edition (Ref: 421.481)
The Airain caliber AM1 is a mechanical bi-compax chronograph watch movement found in Airain Type 20 Re-Edition watches.
In Airain’s own words:
“Saluting her old Army predecessor Valjoux 222, Calibre AM1 will be featuring a hand-wound column wheel chronograph with flyback complication. With her Côtes de Genève decorated bridge, blued steel column wheel and 28 jewels she is an absolute beauty! All carefully crafted by Manufacture La Joux-Perret in La Chaux-de-Fonds, Switzerland.” –Source
Airain AM1 VS AM2:
These two calibers are similar, both mechanical bi-compax chronographs with column-wheel systems. Both have the same hands and subdial layouts. The main difference appears to be that the AM1 has a power reserve of 60 hours and the AM2 offers up to 63 hours (although Airain’s site states +/- 2 hours). Also, the AM1 was manufactured by Manufacture La Joux-Perret and the AM2 is manufactured by Manufacture AMT (Sellita), both located in La Chaux-de-Fonds, Switzerland.
Jewel Count Mystery:
One thing that remains a mystery is that the AM1, produced by Manufacture La Joux-Perret, is most closely related to the LPJ caliber L113-A011 (soignee variant with Geneva stripes) bi-compax chronograph as a base movement. However, the JLP lists the L113 as having 24 jewels and the Airain says the AM1 has 28 jewels (here). Update: on another page, Airain states that the AM1 has 24 jewels, so maybe the initial version was thought to have 28 jewels but ended up being 24? Either way, there are discrepancies on the brand’s own site.