The original automatic Chrono Masters were Citizen’s high end models in the 52 family of movements, which included the relatively well known Crystal Seven range. Several levels of accuracy were incorporated into the Chrono Master line-up – the standard model, the Chronometer, the Special and the Superior Chronometer Special. They also produced hand winding models, and one electro-mechanical (‘X8’) version – for comprehensive information on all the range see this page:

https://sweep-hand.org/the-chrono-masters/

My example is the Chronometer Auto Day Date, with the 33 jewel 5240 movement, and was made in May 1969:

The movement hacks, and the crown is in the hacking position in the above image. Not all of the Chrono Masters came on steel bracelets, but this one did and has 20mm lugs. I’m not convinced that the bracelet is original – catalog pics show a mesh design – and the end links are not a snug fit, so I replaced it with black leather, which was also the original retail option for Chrono Masters:

The eagle motif used exclusively on the dial of the Chrono Masters is repeated in the form of a gold medallion on the back – the wear on this one helped keep the price to an affordable (for me) level!:

The case number is 4-520840 – these can also be found with earlier style number of ACSS2929. The case is in good condition, with no dings, just some light scratches. The crown is signed with the older style ‘C’ mark, which I think was used on all the Chrono Masters:

On the standard and Chronometer models, unlike the Specials and Superior Chronometers, there is no fine adjuster on the balance:

The movement number is stamped near the balance wheel:

This movement run at 18,000 beat per hour, so in good condition this is an accurate vintage piece – they are less likely to suffer from excessive wear that may be found in high beat pieces, and need less frequent servicing too. They are, therefore, worth considering if a high end vintage watch is what you are after.

The Chrono Master name has been retained by Citizen and a modern high end quartz model gives accuracy of +/- 5 seconds per year. That is more likely to be the daily variation of one of the vintage models 🙂