As part of its 20th anniversary celebrations, MB&F has unveiled the Legacy Machine Perpetual Longhorn and Legacy Machine Sequential Flyback Longhorn. These new models retain the groundbreaking movements developed by Stephen McDonnell but add a fresh twist in the form of elongated lugs, or “horns,” that give the watches their name.

Limited to just 20 pieces each, the Longhorn editions feature stainless steel cases and a more muted take on MB&F’s signature style with black dials. The Longhorn is a revival of sorts of a 2009 prototype of the Legacy Machine 1. To ensure good fit across a range of wrists, the longer lugs include dual spring bar holes; one at the tip and another closer to the case.

Initial thoughts

As a fan of MB&F, and especially the work of Stephen McDonnell, I was immediately interested in the Longhorn editions, despite the fact that they’re largely cosmetic variations of existing models. The watches are intrinsically interesting, given their groundbreaking movements, and new versions of good watches are always worth a look.

Visually, the Longhorn editions are more monochromatic than most MB&F designs. Featuring stainless steel cases, black lacquer sub-dials, and rhodium-plated base plates, the Longhorn editions are a departure for MB&F, offering an alternative to the brand’s signature, extroverted style. Notably, the black-and-silver livery was used on the recent LM SE Eddy Jaquet, albeit without the “long horns”.

But there’s no denying the fact these are large watches, each in excess of 44 mm in diameter and 17 mm in height. They are large visually as well, thanks to MB&F’s open-worked house style, even if the muted Longhorn livery tones things down a little. But while previous editions managed the size with the aid of shorter lugs, the namesake long lugs of the Longhorn will make it wear a bit larger.

Fortunately, the Longhorn editions feature stainless steel cases, reducing weight, and offer two sets of spring bar holes, one set near the tips of the lugs, and the other set nearer to the case, to help all potential customers find a satisfactory fit.

Inside, the watches are unchanged from their predecessors, which is to say they house some of the most interesting movements in the industry. Both movements were developed by Stephen McDonnell, who is well-known for his outside-the-box thinking when it comes to solving age-old problems in movement design.

Despite being anniversary editions, the two are priced a little below standard models that are mostly in precious metals. That’s largely attributable to the steel cases, and makes them a compelling proposition. For likely buyers, the pricing is probably less of a concern than getting an allocation, since there will be only 20 of each model.

Longhorn explained

The Longhorn concept dates back to 2009 and the creation of the Legacy Machine 1 (LM1), when the designers could not agree on the optimal placement for the spring bar holes. The prototype LM1 with “long” horns was revealed publicly in 2021 for the LM1’s 10th anniversary, when MB&F put the prototype up for sale at Phillips, where it sold for CHF277,200, with part of the proceeds going to an African rhino charity.

The original Legacy Machine 1 Longhorn prototype

The prototype set the tone for the new Longhorn editions, with a stainless steel case, black lacquer sub-dials, and a rhodium-plated base plate, diverging from traditional case materials like gold or titanium. Today’s Longhorn case also features two sets of spring bar holes to ensure adjustable strap placement, solving the original issue.

The conventional LM case (left) and the Longhorn

The LM Perpetual Longhorn

The Legacy Machine Perpetual Longhorn features the same movement as the original LM QP. Introduced in 2015, the LM QP represented a radical rethinking of the perpetual calendar complication, one of the most delicate mechanisms in watchmaking. Developed by Stephen McDonnell, the LM QP eliminated many of the common weaknesses that had plagued conventional perpetual calendars for decades, such as sensitivity to shock, wear, and user error.

At the core of the LM QP is the “mechanical processor,” a novel component that replaces the traditional ‘grand lever.’ This processor operates as a variable command system, capable of adjusting its operation to account for varying month lengths. Unlike the classical 48-month cam and grand lever arrangement, Mr McDonnell’s processor simplifies the energy flow and reduces the stress placed on components during the end-of-month date changes. The result is a fool-proof perpetual calendar that is not only mechanically efficient but also easier to maintain.

The ingenious mechanical processor found in the LM QP

One distinctive feature of the LM QP is its retrograde date display, which is integrated directly into the calendar mechanism. The date hand performs an instantaneous counter-clockwise jump at the end of the month, a process driven by a coiled spring that gradually accumulates tension throughout the month. This design ensures smooth operation while maintaining the visual symmetry of a circular date scale, and ensures the hand switches directly from the last day of the prior month to the first day of the next without transiting the dates in-between.

The LM Sequential Flyback Longhorn

The MB&F Legacy Machine Sequential Flyback Longhorn builds upon the LM Sequential EVO, the brand’s first chronograph, introduced in 2022. Naturally, the flyback version adds a dual flyback function to its already innovative twin-chronograph movement. Also developed by Stephen McDonnell, the movement links two independent chronograph mechanisms with a single escapement, allowing them to operate separately or simultaneously via the Twinverter—a binary logic gate that toggles their states.

The new Longhorn model retains the Flyback’s movement, and features a 72-hour power reserve, achieved through twin barrels driving symmetrical going trains. The vertical clutches integrated into each train ensure smooth chronograph operation by eliminating backlash, while jewelled bearings within the clutches minimise friction for consistent performance.

Key Facts and Price

MB&F Legacy Machine Perpetual Longhorn

Diameter: 44 mm
Height: 17.5 mm
Material: Stainless steel
Crystal: Sapphire
Water resistance: 30 m

Movement: Perpetual calendar movement developed by Stephen McDonnell
Functions: Hours, minutes, day, date, retrograde leap year, and power reserve indicator
Winding: Hand-wound
Frequency: 18,000 beats per hour (2.5 Hz)
Power reserve: 72 hours

Strap: Leather strap with stainless steel folding buckle

Limited edition: 20 pieces
Availability: At MB&F retailers and MAD Galleries
Price:CHF168,000 excluding taxes

MB&F Legacy Machine Sequential Flyback Longhorn

Diameter: 44 mm
Height: 18.2 mm
Material: Stainless steel
Crystal: Sapphire
Water resistance: 30 m

Movement: Chronograph movement developed by Stephen McDonnell
Functions: Hours, minutes, power reserve indicator and twin flyback chronograph function
Winding: Hand-wound
Frequency: 21,600 beats per hour (3 Hz)
Power reserve: 72 hours

Strap: Leather strap with stainless steel folding buckle

Limited edition: 20 pieces
Availability: At MB&F retailers and MAD Galleries
Price:CHF168,000 excluding taxes

For more, visit MBandF.com.