Mizuno JPX 923 Hot Metal Iron Family (Standard, Pro, HL)

Mizuno JPX 923 Hot Metal Iron Family (Standard, Pro, HL)

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Mizuno JPX 923 Hot Metal Iron Family (Standard, Pro, HL)
  • Mizuno has launched a new JPX 923 Hot Metal lineup.
  • The lineup includes five iron models along with Fli-Hi hybrids.
  • The Hot Metal family ($137.50 per iron) is available beginning next month.
  • The JPX 923 Forged and Tour will launch early next year.

a close up of the cavity of the Mizuno JPX 923 Hot Metal game improvement iron

For 2023, Mizuno is launching five—that’s right, FIVE—new JPX models. The JPX 923 Hot Metal lineup which includes the standard JPX 923 Hot Metal, JPX 923 Hot Metal Pro and a new offering—the JPX 923 Hot Metal HL—will launch in October.

The forged side of the lineup, the JPX 923 Forged and JPX 923 Tour, won’t launch until February.

You can read about both of those here.

Launching Hot Metal in the fall gives Mizuno the opportunity to hit peak golf season in the Sun Belt. That’s the ideal audience for Mizuno’s game-improvement clubs and that should prove especially true with the new JPX 932 HL.

a photo of the Mizuno JPX 923 Hot Metal, JPX 923 Hot Metal Pro, and JPX 923 Hot Metal HL

JPX Hot-Selling

Another factor in putting a fresh collection of Hot Metal on shelves sooner than later is that JPX Hot Metal is the reason why Mizuno’s full-year market share exceeded 10 percent in 2021. That’s up from seven percent in 2018.

While the company is known for its forgings, it’s the standard JPX Hot Metal that’s the company’s biggest seller. No. 2? Hot Metal Pro.

The Hot Metal lineup is a kind of a big deal for Mizuno.

As much as anything, that speaks to Mizuno chipping away at the belief that its clubs are exclusively for better golfers. The company has worked to expand the appeal of its product across a greater range of handicaps and the results are coming through in the sales figures.

While our audience loves Mizuno’s forged stuff, it’s the cast Hot Metal line that’s given Mizuno traction and momentum with average golfers.

a photo of the three irons that make up the Mizuno JPX 923 Hot Metal family

JPX 923 Hot Metal Family

The first thing to keep in mind as we walk through the Hot Metal of the JPX 923 lineup is that technology, materials and construction are consistent throughout. What’s true for one JPX 932 model is largely true for all. The differences can be found in the size of the iron and the specifications of the set.

JPX Hot-ter Metal

Mizuno JPX 923 Hot Metal irons are cast from Nickel Chromoly steel

For the last three generations of product, Mizuno has used Chromoly 4140M. The material served Mizuno well but with the need for more speed ever-present, the company needed a stronger alloy to hit its COR and COR AREA (a Mizuno forgiveness metric the company believes is a bit more robust than Moment of Inertia) goals.

The new material, Nickel Chromoly 4335, is similar to 4140M but the addition of nickel to the alloy gives it additional strength. You won’t find much Nickel Chromoly 4335 in use in the golf industry. Where you will find it is in airplane landing gear, transmission gears and military aircraft.

Thinner Faces

By the numbers, Nickel Chromoly 4335 is 35 percent stronger than the previous Chromoly material, which is how Mizuno was able to reduce face thickness by eight percent.

A thinner face works like a bigger trampoline, which typically yields faster ball speeds.

Nickel Chromoly can handle the increased stress on the face without additional reinforcement. Basically, Mizuno didn’t have to make high stress areas overly thick to keep them from breaking.

Not only are all of the irons in the JPX 923 Hot Metal family faster but Mizuno increased the COR AREA (the portion of the face where COR is above .800) by 16 percent.

Mizuno JPX 923 Hot Metal irons

Variable Thickness Sole

With JPX 923 irons, Mizuno is using a variable thickness design in the sole. As with the face, if you can create more flex in desirable areas of the sole, you can create more speed.

The thin area of the sole is 18 percent larger which allows for more flex and with it—you guessed it—more speed.

TL;DR: The new Mizuno JPX 923 Hot Metal irons aren’t just faster, they’re more consistent. Mizuno thinks JPX 923 will produce the fastest and most consistent balls speeds among the competitive set. You know, distance and forgiveness. That sort of thing.

V-Chassis Design

Thinner faces are great for speed but they can have serious consequences when it comes to sound and feel.

“There are so many high COR golf clubs that sound like hot trash out there,” says Mizuno club designer Chris Voshall.

For a company that habitually leads the league in sound and feel, “Hot Trash” isn’t going to fly.

Fundamentally, V-Chassis is a bit of clubhead geometry to make an ultra-thin faced casting feel more like a forged iron.

Notable in the construction details is that all three JPX 932 Hot Metal designs are single-piece castings.

Mizuno JPX 923 Hot Metal irons feature V-Chassis construction

What’s more, Mizuno isn’t using any foam or goo to dampen vibrations. Apart from adding what Voshall calls “wasted mass,” fillers don’t always improve feel so much as they eliminate it.

“We always want you to feel more,” says Voshall. “Then it’s our to job to make sure you feel the right thing.”

What V-Chassis does is reinforce the cavity iron with a good bit of that being along the topline where, in simple terms, good feel often goes to die.

In technical terms, the reinforced frame helps suppress lower frequencies while allowing more sound pressure at higher frequencies.

(Those particulars won’t be on the test.)

What you might notice in the real world is an iron that’s a bit louder but not “clacky.”

“Hot and solid,” says Voshall. “Not hot and broken.”

With the tech stuff out of the way, let’s take a look at Mizuno’s three JPX 923 offerings.

Mizuno JPX 923 Hot Metal HL

A photo of the Mizuno JPX 923 Hot Metal HL iron

Let’s start with the new model in the JPX lineup, the Hot Metal HL.

As it usually does in the golf equipment space, HL stands for “high launch” and while that seems like it should be desirable in a game-improvement iron, I don’t think I’m sharing much of a secret when I tell you that the industry has been chasing distance at the expense of launch and spin for years.

Sure, for golfers who generate enough speed, the high launch and steep descent angles provided by low and deep centers of gravity sometimes offset the spin lost to stronger lofts. For many average and below-average swing speed players, however, the math behind loft-jacking doesn’t work.

The only way golfers within that demographic are going to get real green-stopping performance is with higher launch (from higher static lofts) and more spin.

A face-on view of the Mizuno JPX 923 Hot Metal HL Iron

To be sure, this time around Mizuno isn’t going to lose its identity trying to better serve a particular segment of golfers. Mizuno isn’t trying to recreate the JPX-EZ or make anything else that would qualify as distinctively un-Mizuno.

There is nuance to the JPX 923 HL design. Technically, the blade length from heel to toe is the same as the standard model. Mizuno stretched the par area (the transition zone between hosel and face) just a bit so it does look a bit longer. So, I suppose it’s fair to say the head is a little longer.

Compared to the standard JPX 923 Hot Metal, the HL has slightly more offset and a slightly thinner topline.

The point I want to hammer home is that while the JPX 923 Hot Metal HL is designed for guy who needs a real game-improvement or even a super game-improvement design, the idea is to give you the benefit of the former (back when game-improvement clubs were still game-improvement clubs) without looking like the latter.

An address view of the Mizuno JPX 923 Hot Metal HL iron

Weaker Lofts! Seriously.

Beyond geometry, the big talking point for JPX 923 HL is that they’re 2.5 degrees weaker in loft than the other Hot Metal offerings. If there’s a downside it’s that, for some golfers, the HL might go shorter.

As we talk about frequently, iron distance sells but it’s not of much value if you’re firing lasers over and through greens.

Here’s my question: Would you give up a little distance if it meant relying on your wedges a little less often?

A toe-centric angle of the JPX 923 Hot Metal HL iron

The Fitter’s Perspective

TXG’s Ian Fraser calls the JPX 923 HL, “the iron that the industry has been crying out for.”

I think—at least I hope—Fraser speaks for most fitters but it’s an inconvenient truth that the HL is also an iron that golf equipment manufacturers have, to the detriment of golfers, been running away from for the better part of the last decade.

Why is Mizuno thinking differently?

A good bit of motivation for creating the JPX 923 HL came from data collected from fittings using Mizuno’s shaft optimizer. In combing through the data, Mizuno found several trends that influenced the design.

Mizuno found that today’s golfers are delivering the club with more shaft lean, they’re steeper into the ball on average and there’s been an appreciable increase in the number of lower swing speed players getting fitted.

As a related aside, Mizuno’s shaft optimizer makes a ball recommendation based on the spin characteristics of the player. The data revealed that the optimizer was consistently recommending higher-spinning golf balls.

The summary version of all of that is that nearly everything in Mizuno’s data suggested that the equipment design world had shifted, arguably over-shifted, towards lower spin.

The JPX 932 HL became answer to question, “How can we deliver more spin with Hot Metal?”.

We’re not talking exclusively about more spin. With higher lofts, the target player is going to experience high ball flight and better all-round performance.

a closeup of the cavity of the Mizuno JPX 923 Hot Metal HL iron

Who is the JPX 923 Hot Metal HL Player?

Mizuno found that the breakeven point between HL and standard Hot Metal is right around a 73-mph 7-iron. If you don’t know your 7-iron speed, it works out to something between 87 and 90 mph with a driver. If you’re below that, Mizuno thinks there’s a good chance you’ll be better served by JPX 923 Hot Metal HL.

For what it’s worth, Mizuno’s fitting suggests we’re talking about 27 percent of male golfers. And, the thing is, despite its recent growth in the game-improvement category, Mizuno still over-indexes with the better player.

The thinking is that golfers getting fitted for Mizuno are likely faster than the real-world average. That means that the percentage of golfers whose swing speeds suggest they’d benefit from the HL is above 30 percent.

To reiterate, the idea behind the JPX 923 HL isn’t to take away distance. Mizuno says the target golfer is likely to maintain carry and maybe even gain distance, albeit with more sensible, more playable landing conditions.

It doesn’t exactly roll off the tongue so it probably won’t catch on, but Mizuno is framing the new Hot Metal as its fastest-stopping fast iron.

Stock shaft options for the Mizuno JPX 923 Hot Metal HL include the Dynamic Gold DG95 and Recoil ESX graphite.

Set-Matching Wedges

For golfers who want their wedges to match their irons or those who might benefit from a slightly larger design, Mizuno is offering JPX Hot Metal HL gap, sand and lob wedges.

JPX 923 Hot Metal (Standard Model)

A photo showing the standard version of the Mizuno JPX 923 Hot Metal iron

We’ve already talked about the tech so all we really need to say is that the standard JPX 923 Hot Metal irons get you the same tech as the HL rolled into a slightly smaller chassis.

The JPX 923 is a textbook game-improvement club. Relative to the market as a whole, Mizuno thinks it’s going to be faster and more forgiving but the sweet area is slightly smaller than the HL.

The center of gravity is a tick higher as well and you’ll find stronger lofts throughout the set. At the risk of stating the obvious, the standard JPX 923 Hot Metal is going to launch lower and with less spin than the HL.

An address view of the Mizuno JPX 923 Hot Metal iron

For the standard JPX 923 Hot Metal (and the Hot Metal Pro), Mizuno has increased the bounce angle on the sole a bit.

Again, this speaks to the data collected with the shaft optimizer. Call it an adjustment for those steeper attack angles. Adding bounce gives Mizuno the ability to bend lofts stronger when fitting calls for it without increasing risk of digging.

Stock shaft options for the Mizuno JPX 923 Hot Metal include the Dynamic Gold DG95 (Regular), KBS Tour Lite (stiff) and Recoil ESX (graphite).

JPX 923 Hot Metal Pro

A photo of the Mizuno JPX 923 Hot Metal Pro iron

The summary of the JPX 923 Hot Metal Pro irons reads like this:

It’s smaller, thinner and touch less forgiving (compared to the standard model).

Beyond the new tech, the most significant change for the JPX 923 Hot Metal Pro is a more compact head design.

Where size is concerned, there is a greater difference between the Standard Hot Metal and the Hot Metal Pro than there is between the Standard and Hot Metal HL.

My takeaway is that, for what it is, the JPX 923 Hot Metal HL isn’t that big and, for what it is, the JPX 923 Hot Metal Pro is surprisingly compact.

An address view of the Mizuno JPX 923 Hot Metal Pro iron

If you’re in the camp that sees that as a benefit, it’s two-fold. First, it gives golfers who like the look of a more compact head an option with plenty of forgiveness.

Second, with a more compact JPX 923 Hot Metal Pro in the lineup, Mizuno took the opportunity to reduce the footprint of its JPX 923 Forged iron a little bit. That should prove extremely popular with the 923 Forged player.

The stock shaft for the Mizuno JPX 923 Hot Metal Pro is the Dynamic Gold DG95 (regular and stiff)

Set-Matching Wedges

Mizuno is offering Hot Metal wedges to pair with the Hot Metal or Hot Metal Pro. While there is a little bit of game-improvement slant to the design (relative to the T-series), it’s comparably minimal.

Golfers won’t have to sacrifice performance as the Hot Metal wedges feature the same Quad Cut grooves as the T-Series.

JPX 923 Fli HI (when HL isn’t enough)

The Mizuno JPX 923 Fli-Hi hybrid

When it comes to optimizing trajectory within the JPX 923 Hot Metal family, Mizuno has one more lever to pull. For golfers who need higher launch than any of the Hot Metal irons can offer, the shaft optimizer (or your fitter) may recommend you add a Fli-Hi or two (or three) to the mix.

Hybrid with Deeper footprint.

The latest iteration of the JPX Fli-Hi is a hybrid with a deep footprint. That low and deep center of gravity is going to give you higher launch.

The ripple is that hybrids are typically longer than the long irons they replace (and the shaft length is a quarter-inch longer to begin with) so Mizuno has borrowed a page from the original playbook of the new Ben Hogan.

Instead of putting a number (e.g., 3, 4, 5) on its Fli-Hi hybrids, Mizuno decided to stamp the loft instead.

While that might seem like Mizuno is complicating things, the goal is to simplify things for the golfers.

The loft of a 5-iron in the JPX 923 Hot Metal HL set isn’t the same as it is with the standard Hot Metal. Rather than play to the middle (and potentially miss everyone), Mizuno wants golfers to check the loft of the long iron they’re replacing and find the Fli-Hi that mostly closely matches.

For example, if you’re looking for the Fli-Hi replacement for your JPX 923 Hot Metal HL 5-iron, you’ll want the 25-degree model. If you’re making the same swap in a standard JPX 923 Hot Metal set, you’ll want the 22-degree Fli-Hi.

No Putts Given Bonus Edition

Be sure to check out this special bonus edition of No Putts Given where we discuss the new JPX 923 lineup and so much more with Mizuno’s Chris Voshall.

Specs, Pricing and Availability

Retail price for all Mizuno JPX 923 Hot Metal clubs, including the Fli-Hi hybrids, is $137.50 per club with any shaft or grip in the Mizuno no-upcharge lineup.

Retail availability begins Oct. 8.

For more information on the Mizuno JPX 923 Hot Metal iron lineup, visit Mizunogolf.com.

JPX 923 Forged and JPX 923 Forged Tour

An image of the copper unederlay of the Mizuno JPX 923 Tour irons

Mizuno has also released two new forged offerings. Our story on the new JPX 923 Forged and JPX 923 Tour irons can be found here.

For You

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Tony Covey

Tony Covey

Tony Covey

Tony is the Editor of MyGolfSpy where his job is to bring fresh and innovative content to the site. In addition to his editorial responsibilities, he was instrumental in developing MyGolfSpy's data-driven testing methodologies and continues to sift through our data to find the insights that can help improve your game. Tony believes that golfers deserve to know what's real and what's not, and that means MyGolfSpy's equipment coverage must extend beyond the so-called facts as dictated by the same companies that created them. Most of all Tony believes in performance over hype and #PowerToThePlayer.

Tony Covey

Tony Covey

Tony Covey

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      11 months ago

      The Mizuno JPX-923 Hot Metal, High Launch irons became available in Canada on Oc t 15. I was at the Golf Town store the day trying them out in the hitting bay. From the first swing with them I was sold. I spent an hour making effortless swings with a variety of them. Every shot felt buttery smooth, contact with the ball was effortless, the ball flights were amazingly consistent, and I was getting about 5-7 yards extra carry with them. They were easy to work the ball both left and right.

      Needless to say, I left the store with a new set of sticks in hand. I was at the course for the next few days putting them through their paces and I am really pleased with how they perform. Next order of business is finding someone to take my Ping G400’s off my hands.



      1 year ago

      One thing I’d LOVE to see (Hey MGS…hint hint hint) is a New Model vs. Old Model test. I don’t care which Brand it is, but would love to see the test number differences from New Model Club vs Old Model Club. Could be some real eye openers in there….or maybe some inconvenient truths? Like JPX 923 Hot Metal vs JPX 921 Hot Metal.



      12 months ago

      Yes, this would be helpful in determining when to do an upgrade/replacement. While year over year (or every two years depending on the brand) might not show significant delta in performance, I could do multiple comparisons to get an idea on performance gains (distance, dispersion and forgiveness) for 4 to 6 years to determine if there is benefit in upgrading verses the costs.



      1 year ago

      Nicely written article. Mizuno always puts out quality equipment. See that they are also in the stronger loft game; their feel has always been excellent. Suggest that some prrof read again, as there are some 932 instead of 923 entries…



      1 year ago

      Yesterday I tried their 923 Hot Met 7-iron 28 degree. loft demo. A 28 degree loft is typically a 6-iron. If the rest of the set lofts are off this much that’s messed up. Aside from that, not much offset, good weight and not a thick top line.



      1 year ago

      I have 921 HMs with True Temper Elevate 95 shafts. I think TT Elevates are supposed to provide higher launch quicker stopping for the low spin irons, which sounds like the HL.


      duh golfer

      1 year ago

      When will Mizuno announce their next driver? This year, next year, or ???


      Gerry H

      12 months ago

      The STZ-220 came out in Feb of this year, really can’t see them launching a newer driver until late next year for Southern Hemisphere and ROW early 2024, just my guess


      Eric Hutchens

      1 year ago

      Big fan of the JPX Line. Great Job Mizuno and Mygolfspy!



      1 year ago

      Great article Tony…..well written!!
      Mizuno continues to gain market share each year through great product offerings, not by creative marketing or paying handfuls of professionals to play their equipment. Mizuno offers an iron for any level of player and the drivers & fairways are comparable to anything out there. In our retail store, the JPX Hot Metal has been our best selling iron for the past 5 years….against the other major golf manufacturers.


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