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Ball Caliber Rrm7309 C

Ball Watch Caliber RRM7309-C

Ball Caliber Rrm7309 C

Brand Ball Watch Company
Caliber Number RRM7309-C
Movement Type Automatic, self-winding mechanical
Beat Rate
28,800 vph, 4 Hz
Lift Angle
50 degrees
Power Reserve
80 hours
Rotor Style
Anti-Shock Device
Silicon Hairspring?
No (see below)
Hand Count 3
Functions Central hours; central minutes; central sweeping seconds; date at 3:00
Hacking Seconds?
Includes ribbing, perlage and spiral patterns
Country of Manufacture Switzerland, Swiss made
Known Models
Engineer M models (Add your watch to the comments below…)

The Ball Watch Co. caliber RRM7309-C is a Swiss made automatic watch movement that was introduced in 2018. The layout of this caliber is a 3-hander with a date at 3:00. The “C” stands for chronometer or COSC. The “M” on the models featuring this movement stands for manufacture caliber.

If you look closely, it appears to be a typical sized movement, mounted on a larger mainplate with a perlage background. This gives the movement an overall diameter of 34.24mm (compared to an ETA 2824-2 . The single screw balance bridge is positioned in a way that gives the balance wheel the appearance of floating when looking at it from the top. Adding to the interesting choice of dimensions, the rotor is also oversized, filling in the gaps between the bridges and the mainplate.

Movement Text: RRM7309 / Serial/COSC number (for example B00196) /  SWISS MADE / TWENTY-FIVE (25) JEWELS / MANUFACTURE

Rotor Text: OFFICIAL STANDARD / RR (Railroad) / BALL WATCH COMPANY / some images also show “SWISS MADE” and TWENTY FIVE JEWELS (25) around the ball bearings – this may be just for the video to accentuate those points to the viewer, since real images of the movement do not feature the same rotor text (but let’s face it, for an in-house movement, the brand does not provide much information/images).

Ball Watch Caliber Rrm7309

Brief Brand History:

Ball Watch Company started out as an American watch brand founded in 1891 (Cleveland, Ohio). The company bought private label watches from various manufacturers (see below) and sold them with the Ball name on them. There is not much in terms of official history provided by the company as to how they ended up being headquartered in La Chaux-de-Fonds, Switzerland and owned by Hong Kong based Asia Commercial Holdings Ltd – other than the name of the brand being sold to private investors in 1990, when the brand reemerged as a Swiss watch company.


Although the brand markets this caliber as an in-house movement, it appears that the extent of it being “in-house” is limited to design and assembly. As far as manufacturing of components, does Ball have full control over a vertical manufacturing process of their movements in their own facilities? Or are parts made to order based on specs provided to their manufacturer, then assembled and tested at their own facilities? Has anyone been invited to a Ball factory tour yet? Caliber Corner has not been able to confirm that yet. As more information is discovered, this page will be updated.

If the movements are truly not made in Ball facilities, then it could be another example of a Swiss watch brand doing their best to capitalize on the growing interest and marketability of the term in-house. It also certainly would make the random low quality image of a watch manufacturing facility on their Chronometer Manufacture Calibers page comical.

Brands are now finding ways to use in-house as well as manufacture, which technically should be distinguished by one being one being manufactured by the brand in-house, and the other being manufactured exclusively for the brand by an outside (out-of-house) movement manufacturer aka movement house.

Editor’s note: Lest we forget that most Japan made movements are also in-house, yet the Japan based watch manufacturers have not fully hopped aboard the in-house hype train – so the term doesn’t get thrown around as much in their marketing.

In Ball’s own words:

“The road to independence is not marked by comfort, but rather unstoppable courage. With our growing range of in-house movements, each known as a Chronometer Manufacture Caliber, BALL Watch Co. continues to take bold steps forward. The result of years-long development combined with special material, refined craftsmanship and stringent criteria, every caliber is COSC certified and ready for the adversity of adventure.” –Source

And in reference specifically to the RRM7309-C:

“Our first in-house movement, Chronometer Manufacture Caliber RRM7309-C is defined by precision, efficiency and reliability. As a COSC certified movement, it has undergone rigorous testing by the Swiss Official Chronometer Testing Institute while also meeting the high standards set by our founder and watchmaking pioneer, Webb C. Ball. Going beyond ordinary autonomy, the caliber’s 80-hour power reserve still maintains a frequency of 28,800 beats per hour (4Hz), ensuring accurate timekeeping even when unworn. On some models, a sapphire crystal case back provides a window to the polished finishing and pristine precision hard at work.” -Source same as above

Editor’s note: It is interesting that for the brand’s first so-called in-house movement, they are also referencing the railroad standards set by Webb C. Ball, when even back when Ball was a real American watch brand, they did not manufacture their own watches. The (relatively high-priced) vintage Ball pocket watches that can be found on eBay today are mostly pieces of history, but not actually pieces that demonstrate Ball’s manufacturing abilities. All of this, buy the way, is not meant to discount the influence and importance that the “RR Standard” had on the American watch industry – and subsequently everyone else.

As the following excerpt from Wikipedia puts it:

“His original jewelry business in Cleveland grew into the Ball Watch Company (currently headquartered in La Chaux-de-Fonds, Switzerland), which used other watch companies’ movements, perfecting them and then reselling them. Ball Watch Company also ordered watches complete from other watch companies. Ball used movements from the top American manufacturers, Elgin, Hamilton, and Waltham. The company switched to Swiss Avia movements as early as the 1940s.” –Webb C. Ball entry on Wikipedia

RRM7309-C VS RRM7309-CS:

There is a similar caliber RRM7309-CS which shares all of the same specs with the RRM7309-C, except that the “S” on the end of the caliber number stands for “silicon”. The RRM7309-CS is equipped with an anti-magnetic silicon balance spring, giving it an anti-magnetism rating of up to 2,500 G / 200,000 A/m.

Note: While Ball’s official site calls the silicon version the RRM7309-CS, the description on their Engineer M Pioneer YouTube video (below) refers to it as RRM7309-S. Brand who can’t agree on one way of spelling the caliber number undoubtedly cause caliber confusion in the community. Also note that regardless of being a C, CS or S version, all of the caliber in this family appear to only have “RRM7309” engraved on the movement.

For example, the video for the Engineer M Pioneer (screenshot below) says the movement has a silicon hairspring, but the movement is only signed RRM7309:

Ball Watch Caliber Rrm7309 C


Ball claims that the accuracy of the RRM7309-S (or CS?) (the one with the silicon hairspring!) is within a range of -2 to +5 seconds per day, a rating they also state is “a 30% increase in precision as compare [sic] to the COSC standard.”

It is unconfirmed whether that accuracy claim is also applied to the non-silicon caliber being discussed on this page. However, accuracy reports across various platforms are consistently in high praise of the RRM7309 series. Please be sure to add your experience to the comments below…

Anti-Shock Device:

In some images, the RRM7309-C is equipped with a Novodiac shock absorber. In others, they are using Incabloc. There is no explanation given for the inconsistency. Please comment below which one your watch has…

Ball Caliber Rrm7309 C Balance Wheel Regulator

Engineer M Series:

The Ball Calibre RRM7903-C is found in the brand’s Engineer M line of watches.The M stands for manufacture caliber.

“Magnificent. Majestic. Manufacture. All befitting descriptors of the Engineer M series, which exclusively features our manufacture caliber movements. Designed and built completely in-house, this collection of luxury watches represents the apex of our heritage and pioneering spirit.” –Source

The price range for a watch with this movement spans from $2,899 USD up to $4,049 USD, depending on case metal and band.

Video: Engineer M Pioneer

Video: Ball Watch Corporate

Additional Resources:

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