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First look: New Mizuno Pro irons

December 10, 2021
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WHAT YOU NEED TO KNOW: Mizuno Pro, the latest family of forged irons from the company famous for its patented manufacturing processes, caters to three kinds of players looking for stylish design and compact scoring irons, but with gradually increasing levels of horsepower. The Mizuno Pro 221 is the company’s upgrade of its classic muscleback blade, featuring more mass behind the hitting area. The Mizuno Pro 223 is a single-piece forged iron where the long- and mid-irons boost ball speed through unique materials and construction. The Mizuno Pro 225 brings the most possible distance and forgiveness of the group with a multi-material hollow construction all the way through the 8-iron.

PRICE: $187.50 per club for all three models. Available Feb. 3.

THE DEEP DIVE: Mizuno has long been heralded for its precision. (The story is that founder Rihachi Mizuno required the company’s baseballs to bounce precisely to his eye level—4 feet, 5 inches—when dropped from a height of 16.5 feet, or they were rejected.) So it’s no surprise that its latest forged irons, the Mizuno Pro 221, 223 and 225, were conceived with that same attention to detail that’s been at the heart of the company for over a century. As David Llewellyn, director of research and development, puts it, “We’re working in small increments.”

Of course, those increments might be small, but Llewellyn believes that the upgrades to the traditional muscleback blade (221), the forged cavity-back players iron (223) and the hollow, fast-flexing face insert players distance iron set in place big moves forward.

That sort of advancement seems hard to imagine in the muscleback blade Mizuno Pro 221. It’s a single-piece forging, and while Mizuno’s patented “grain flow HD” forging process concentrates the density of the 1025E carbon steel in the hitting area, what really can advance the paradigm of a muscleback blade? Again, says Llewellyn, small increments. The Mizuno Pro builds on the framework of the MP-20 but does so with some specific new directives.

“There’s been a common theme with the better player to make more compact short irons, and that was the job done here,” he said. “We’re going to make more compact scoring irons, we’re going to improve the feel, and we’re going to look for opportunities to fine tune the center of gravity.”

Llewellyn said a “more aggressive, thicker muscleback” area improves that feel, as does the copper underlay in the plating process that debuted with the MP-20 and is again featured throughout the three new Mizuno Pro irons.

As for fine tuning the CG, it’s not like the 221 is moving it in dramatically new directions forward or back, high or low. Rather, it’s more about the way the CG flows through the set and making it more gradual and predictable from long-irons to short0 than in the MP-20. That helps maintain consistency in a better player’s swing. For comparison, the 221 also will have shorter distance to the CG from the hosel axis than Mizuno’s JPX 921 Tour iron.

“We’re talking about a couple tenths of a millimeter, but it’s just another opportunity to get that sweet spot to be as consistent as possible,” he said. “Let’s take what we know is good about the MP-20 and make it even better.”

With the Mizuno Pro 223, “better” is both more aggressive and hidden. Though still very much in the shape of a players’ cavity back iron, this design makes a more overt push toward distance. Notably, the long and middle irons on the 223 are forged from a variant of chromoly steel, the same metal that has been at the root of the company’s top-selling JPX 921 Hot Metal game-improvement iron and the JPX 921 Forged players-distance iron.

“Even in the shallow players cavity category there’s definitely a trend toward COR,” said Llewellyn, referencing coefficient of restitution, the measurement of how a face flexes to produce more ball speed.

“So we’re putting the technology in the set where it needs to be, where it can help spread out your distance gaps, and then where you want your one-piece, grain-flow forged shallow cavity in the 8-iron through gap wedge it’s 1025E.”

The distance quotient on the 223 gets an additional boost with hidden milled slots in the soles of the 4- through 7-iron. Those slot shapes are distinct for each iron, with the slot on the 4-iron being wider and deeper for maximum distance enhancement. The slots on the 5- and 6-iron are slightly T-shaped to provide a measure of heel-toe weighting, while the slot on the 7-iron is as thin as possible to smooth the transition to the one-piece forging in the 8-iron.

That two-tiered approach to an iron set is also the blueprint for the Mizuno Pro 225, a players-distance set that features a hollow tungsten-weighted design in the long and middle irons and a two-piece partially hollow construction in the short irons. Again, the high-strength chromoly steel is part of the thin face construction of the 2- through 8-iron, which features a forged 4135 chromoly face and neck and a soft 431 stainless steel back piece. The face features a new variable-thickness design to improve ball speed throughout.

On the 2- through 7-iron, a centered, 28-gram tungsten slug sits low within that back piece. It puts the CG lower and deeper while still allowing the face to flex. The 8-iron features the same hollow construction without the tungsten to smooth transition to the partially hollow construction starting with the 9-iron. The short irons feature a forged 1025E carbon steel face and neck with a 17-4 stainless steel cap over the muscleback area.

Even though it’s the most aggressive distance iron in the Mizuno Pro lineup, Llewellyn said there was an intent to “slim it down but not lose any distance” compared to the MP-20 HMB. In essence, to give it a more classic players look, as opposed to the look of the company’s Fli Hi utility irons.

“In the MP-20 HMB we just took the idea of the Fli Hi shape and tried to blend it into a set of irons,” he said. “In this case, though, we don’t need low profile long irons. Let’s take normal looking long irons and blend them to more compact scoring irons. We said let’s just make this look like a proper set of irons.”

While others in the hollow iron space are often filling the middle of their designs with a polymer, Llewellyn said there are other ways to get the feel right: “It’s a higher COR face with a more rigid body,” he said of the completely hollow Mizuno Pro 225. “That’s how we’re controlling the sound, with a more rigid body.”

The Mizuno Pro 221, 223 and 225 irons will be available at retail Feb. 3 ($187.50 per club).