Why the New Mizuno JPX 925 Forged Irons Confuse Me

I must admit that the new Mizuno JPX 925 Forged irons have me a little mixed up.

Not that I’m confused about whether the clubs are any good. Mizuno’s JPX line has been a top performer in MyGolfSpy testing since Hot Metal became a thing. I’m also not confused over in which category the JPX 925 Forged belongs.

It’s most certainly a player’s distance iron.

What’s confusing is where it belongs on the player’s distance continuum.

Like its predecessor, the Mizuno JPX 925 Forged is compact for a player’s distance iron but Mizuno is touting forgiveness that rivals game-improvement irons. On the other hand, the JPX 925 chassis is noticeably larger than a player’s blade or cavity-back but Mizuno tells us it sounds and feels more forged blade-like than even a Mizuno Pro 243.

Conversely, its ball speed and MOI are in the same neighborhood as the TaylorMade P790 or PING i530 despite its noticeably smaller chassis.

And don’t get me started on the thin (for the category) sole and topline.

After our meeting with Mizuno, it seems the JPX 925 Forged is a multi-piece player’s distance iron that’s a single-piece forging designed for ball speed that sounds, feels and plays like a blade while at the same time being forgiving and workable.

One more thing: For a company not prone to hyperbole, Mizuno is saying the performance increase in the JPX 925 Forged over the 923 Forged is the most dramatic it’s seen since the JPX Forged line began more than a decade ago.

See why I’m confused?

Mizuno JPX 925 Forged: New from the neck up

Mizuno launched the new JPX 925 Hot Metal lineup last September but the forged family member was conspicuously absent. That was due to a planned fall launch for the JPX 925 Forged in Japan.

From the ground up, the Mizuno JPX 925 Forged is very different from its predecessor, the 923 Forged. Specifically, it isn’t a one-piece billet forging anymore. Mizuno is using an entirely new production process with the 925 Forged.

As mentioned, the 923 Forged was a one-piece forging. The 8-iron through gap wedge were single-piece 1025E Pure Select Mild Carbon Steel forgings while the 4- through 7-irons were Grain Flow Forged 4120 Chromoly. Mizuno would insert a milling tool through a micro-slot in the sole to create a variable-face thickness for those longer irons. From that approach, the best Mizuno could do was thin the sweet area down to about 2.3 millimeters.

For the 925 Forged, Mizuno uses new, multi-million-dollar forging machinery and a new process to make the face even thinner. Instead of forging the entire head, Mizuno now is single-billet forging the neck, face and topline and welding on a 431 stainless steel sole piece.

With this new construction, Mizuno can now mill the back of the clubface directly rather than through the micro-slot in the sole. That means Mizuno can get even more aggressive, not to mention creative, with that milling.

“We’re now at 2.1mm thickness in the impact zone, dropping down to 1.5mm around the perimeter in the flex zone,” Chris Voshall, Mizuno USA Golf Product and Marketing Manager, tells MyGolfSpy. “That’s a 30-percent decrease in face thickness. When you can go that much thinner, that means a massive jump in performance.”

Bang-squish-squeeze

Forging is more involved than simply pounding the snot out of a molten hunk of metal until it looks like a golf club. As with any other manufacturing technology, the forging process is evolving. That new machinery we mentioned is a prime example. Mizuno uses a hammer press and a hydraulic press to forge its irons. The JPX 925 Forged uses an updated and much more sophisticated hydraulic press for the secondary forging.

The new machine allows Mizuno to vary the pressure at different points in time while compressing the head.

“We’re now able to control the pressure down to where we get to the face,” explains Voshall. “Once it starts to compress, we can control how it compresses and the pace at which it compresses. That allows us to get a much thinner face.”

If it helps, think of the old hydraulic press as a bang-bang machine. The new hydraulic press is more of a bang-squish-squeeze machine.    

Mizuno JPX 925 Forged: The science of feel

Any seasoned club designer can tell you a forged iron crafted poorly with bad geometry can feel like hot garbage. Conversely, a cast iron well-crafted with intelligent geometry can feel just as sweet as the best forging.

Golfers have a unique, not to mention subjective, vocabulary when describing feel. Buddah or buttery-soft are effusive, positive terms. Squishy? Not so much.  Solid and hot are good feels but clanky, clicky and clacky aren’t. Neither is their non-alliterative synonym, tingy.

Solid, however, isn’t the same as hot. Neither is it the same as buddah. No matter how you describe it, what we call “feel” is directly related to vibration and sound.

“Vibrations are great,” says Voshall. “But if they don’t last very long, you won’t feel very much. If they last for a long time but at the wrong frequencies, it can feel like crap for a long time.”

Additionally, when faces get as thin as they are on the JPX 925 Forged, tingy very much comes into play. Single-piece forging and geometry let Mizuno keep tingy under control.

“By forging that topline, we control the geometry of the area underneath,” Voshall explains. “That’s the area that causes tingy so reinforcing that area delivers a more solid feel.”

Additionally, Mizuno has identified sound frequencies that lead to tingy – roughly the 6,000 to 7,000 Hertz range. The reinforced topline as well as the diagonal sound bar across the back of the cavity help mitigate those vibrations.

“This is going to sound and feel more solid and more blade-like than even the Mizuno Pro 243 does,” says Voshall. “The 243 doesn’t have as much reinforcement. This one feels softer throughout the set.”

Triple soles and gravity centers

The new hydraulic press also opens up new mass property doors for the JPX 925 forged. CG distance is a prime example.

CG distance measures the distance between the clubhead center of gravity and the shaft axis. The shorter it is, the more control you have to “work” the ball. The farther it is, the higher the COR and the larger the sweet spot. You normally have to choose one or the other.

“With the new construction and the welded-on back piece, we can strategically control the geometry,” says Voshall. “We can bring the CG distance closer to the shaft axis while still boosting the sweet area. It’s more controllable and more forgiving. If you can pull both off, then you’ve engineered something better.”

The JPX 925 Forged also has a triple-cut or V-shaped sole, something Mizuno couldn’t do on previous iterations. Since face milling now is done from the back rather than through the sole, Mizuno can add bounce on the leading edge, reduce camber in the middle and aggressively bevel the trailing edge.

“It’s a sole that will enter and exit the turf cleaner,” says Voshall. “It’s also going to allow us to have a more uniform effective sole width.”

The 7- to 8-iron sole transition has traditionally been a bit hinky. Mizuno’s new construction method allows for much thinner soles throughout the set and a smoother 7- to 8-iron transition.

“We’re increasing COR, we’re increasing ball speed and we’re adding forgiveness,” says Voshall. “But we’re making a sole that plays thinner than it ever has before, one that’ll enter and exit the turf quickly.”

JPX, Mizuno Pro and the irons market

You can’t call today’s irons market a boom but you can’t call it a bust, either. If anything, the market is in a bit of a stagnant decline. OEMs have to defend their market share while also trying to steal a little bit out of someone else’s sandbox.

“Custom orders are way up but stock orders are way down,” says Voshall. “Two years ago, everybody had one on the rack and 10 in the back. Now everyone’s running lean on inventory and relying on quick custom turnaround.”

Mizuno has always had a cult following but as recently as 2020 it was a fairly small cult. The MP-20 line had a 2.6-percent market share that year while the JPX 919 was at 3.3 percent. A year later, the JPX 921 line started a market shift for Mizuno, grabbing an 8.7-percent share all by itself. By 2023, Mizuno owned a 12.6-percent market share in irons with the JPX 923 holding a nearly 10-percent share all by itself.

Early returns for 2024 show Mizuno’s market share hovering at 13 percent with JPX making up nearly 80 percent of that total. JPX by itself has a bigger iron share today than all of Mizuno did in 2020.

 What does that mean? It means forged, Tour-level blades are nice but JPX buddahs the bread.

Mizuno JPX 925 Forged: Specs, price and availability

The JPX 925 Forged loft matrix isn’t the strongest in the player’s distance category but it is slightly on the stronger side with a 30-degree 7-iron. Mizuno has weakened the lofts slightly on the 9-iron, pitching and gap wedges for better gapping and transition.

Mizuno is doing something unusual by offering a blacked-out JPX 925 Forged at launch. Usually, OEMs will release a black version of an iron a year later to give the line a second-year sales boost. Mizuno, however, is marching to the beat of its own drummer.

The blacked-out finish is what Mizuno calls a premium PVD. The finish goes right over the soft white satin, a rougher finish that allows the PVD to adhere better. The face is a lighter gray thanks to a face blast so it won’t show impact marks.

The standard JPX 925 forged irons come stock with the KBS C-Taper light shaft and the Golf Pride MCC grip in black/gray. The blacked-out model comes with the Dynamic Gold Tour Issue Mid 115 shaft in Black Onyx and the black/gray MCC grip.

As always, Mizuno has one of the most extensive no-upcharge shaft collections in the business.

The chrome Mizuno JPX 925 Forged irons run $200 per club and will be available for lefties and righties. The blacked-out version is right-handed only and runs $215 per club.

Presale starts Jan. 23. They’ll hit the stores Feb. 6.

For more information, visit the Mizuno Golf website.