Mizuno JPX925 Hot Metal Irons – Hot Metal, Hot Metal Pro and Hot Metal HL

For golf equipment enthusiasts, Fall is a special time. We aren’t talking about leaves changing colors or crisp mornings here though. We’re talking about golf clubs; specifically, Mizuno irons. The company’s annual Fall release always seem to come at the perfect time and breathes life into gear junkies worldwide. Fall belongs to Mizuno and 2024 is no exception. The new JPX925 Hot Metal irons series is here and better than ever, giving us all a reason to use these last few months of the golf season to their fullest. 

Following the success of the JPX923 Hot Metal series, Mizuno is again embracing the concept of bringing a plethora of fitting options to consumers, with the 925 Hot Metal line consisting of three different irons and four Fli-Hi loft options. The line retains the easy-to-understand naming convention used with the JPX923 line, consisting of Hot Metal, Hot Metal Pro, and Hot Metal HL options. 

Dave Llewellyn, Director of R&D at Mizuno said, “With the JPX line, we are pushing the boundaries of golf club engineering. The new Hot Metal iron family introduces a multi-material design, strategically incorporating tungsten into our Nickel Chromoly designs, enhancing distance with impressive height and spin. With three distinct models to choose from, each offering extensive custom fitting options, we uphold the quality and craftsmanship Mizuno is renowned for. We are dedicated to continually setting new standards of performance in the industry”

Mizuno JPX925 Hot Metal Irons

The company is leaning on the JPX platform, which has always served as their most forward-thinking line in terms of materials and technologies, to deliver distance, accuracy, and Mizuno’s renowned feel. They aim to reach as many players as possible with a plethora of fitting options and technologies. 

Bill Price, Mizuno’s Director of Custom Fitting notes, “Whether a golfer needs added height, a slimmer profile, more spin, a tailored lie angle, or any of more than 50 unique shaft options, our new JPX range and enhanced PFS System and Software ensure they receive the optimal fit for their game.”

JPX925 Hot Metal Key Technologies

JPX925 Hot Metal lineup features hidden tungsten

Each of the irons in the JPX925 Hot Metal line offers a unique user experience, but all three share the same core technologies. The differences between the irons can be boiled down to how the heads are shaped and how they are configured. This year’s iteration of JPX925 Hot Metal places a great deal of focus on utilizing high-end materials, and how those materials create opportunities for a complete under-the-hood redesign. Let’s take a look at what the 925 line has going on. 

Nickel Chromoly 

The Mizuno JPX925 Hot Metal

JPX925 is Mizuno’s second line to utilize Nickel Chromoly, and it’s contributed greatly to the success of the JPX923 Hot Metal irons. Since its introduction in the 923 series, the company’s R&D group has had time to learn exactly what it’s capable of and how they can utilize it best to maximize performance. This has allowed them to really push the boundaries with their face design. The bottom line is that Nickel Chromoly is known for its remarkable strength-to-weight properties, meaning it can be used to create aggressively thin iron faces that produce the exceptional speed and forgiveness the Hot Metal line is known for. In addition, it retains a level of malleability that allows for easy hosel adjustments. 

CORTECH Design featuring Contour Ellipse Face

As we stated, everything about how the JPX925 Hot Metal series is designed goes back to Nickel Chromoly. That includes a completely redesigned face. We hear the term “redesigned” often with golf club technology, often to the point that it starts to lose its meaning, but Mizuno’s new CORTECH multi-thickness profile is significantly different than what they’ve produced in the past. It features a Contour Ellipse Face that probably will make more sense when illustrated. 

CorTech inside the JPX923 irons

In the illustration of the JPX923 HM above, we can see how the CORTECH face was previously implemented. Of note is the thicker center area that descends to the sole, surrounded by two slightly thinner “ears”, and eventually an even thinner outer portion. 

CorTech inside the JPX925 irons

As you can see by the graphic above, the JPX925 Hot Metal’s face is completely different. The Contour Ellipse design retains the most thickness in the center of the face, but it gradually thins out to just 1.2mm before slightly thickening at the edges. Notably missing is the extension of the thickest portion that ranges to the sole in the JPX923. In essence, Mizuno is creating an extremely efficient trampoline here. One that they say will perform with impressive consistency, whether you are “jumping” in the center or more towards the outer areas. The new face design has been implemented in the 4 to 8 irons because the effectiveness of this type of technology lessens as loft increases. 

Variable Sole Thickness and Seamless Cup Face

Every trampoline needs a frame, and believe it or not, the construction of that frame can greatly impact how it performs. Mizuno’s goal with all this is to maximize what they call CORAREA, which is simply their way of describing the portion of the face that produces the highest ball speeds and ball speed retention. The JPX925 Hot Metal irons feature a Balanced Stability Frame and Seamless Cup Face, but the real innovation lies in the Variable Sole Thickness. 

As we can see above, the sole portion that lies directly against the CORTECH Face is shaped in a way to provide varying levels of thickness that (in some ways) mimic the Contour Ellipse design. This seems like a tiny detail, but it allows the sole to act as a hinge and actually flex too, amplifying the face’s ability to flex. 

Graph showing Peak COR comparing Mizuno JPX925 Hot Metal irons to all others on the market

We know what you are thinking – what does that all mean to me?  The chart above should help you understand after a quick explanation. Each dot on this graph represents a specific 5 iron. We’ve removed the names, but these are all modern, name-brand irons you should be familiar with. The Peak COR (how hot the face is) is illustrated on the X axis (bottom). The CORAREA (the portion of the face that produces high COR) is illustrated on the Y axis. As you can see, the JPX925 line doesn’t really have an equal here. Yes, the Hot Metal Pros sit a bit under the line for CORAREA, but this was an intentional decision by Mizuno since that particular iron is built smaller by design. You’ll have to take our word for it, but there are some very heavy hitters on this chart, and frankly it makes us beyond excited to get the 925’s on the golf course. 

Multi-Material Construction with Tungsten Weighting

We apologize for pulling out the Billy Mays trope, “But that’s not all.” As impressive as the changes to the CORTECH Face are, the JPX925 series marks another significant change for Mizuno. They are introducing multi-material design into their irons for the first time in the form of Nickel Tungsten. 

The 11g Tungsten weight is hidden from view in the cavity, but the picture above should show both its placement and some of the subtle shaping Mizuno incorporated. You’ll quickly notice that it’s low on the club head, but close inspection also reveals that it’s slightly forward oriented. The use of tungsten isn’t mysterious. Companies use it to manipulate weight placement. Specific to the JPX925 Hot Metal irons, it’s being used in the 4 to 7 irons to induce higher launch angles and move the sweet spot slightly lower on the iron face. This should result in steeper descent angles, making it easier to hold greens.  

Balanced Stability Frame and Weighting Changes

Before we dive into this feature of the JPX925 Hot Metal irons, it’s worth having a quick lesson how blade size can impact how an iron behaves in the swing. Long blade sizes have a definite benefit in the sense that they afford a greater surface area to build hot, forgiving faces. However, as blade sizes increase it can be more difficult to close the club face at impact. This doesn’t really mean that long blade sizes are “fade biased”, but it can have an impact on one’s ability to move the ball left at will. 

Again though, companies that are trying to make long and forgiving irons have to be careful that they don’t alter the balance of blade size so much that it impacts the ‘sweet area’ of the club face. Mizuno looked for a way to address this challenge and made some changes to how they balance out the JPX 925’s. They reshaped and removed weight from the toe area to improve your ability to close the club face at impact, which should have a slight effect of making it easier to draw the golf ball. 

Harmonic Impact Technology and Acoustic Sound Ribs

Last on the technology list, but certainly vital to Mizuno’s identity, are a couple items the company is using to ensure they are delivering irons with premium feel in the JPX925 Hot Metal line. Looks and feel are central to Mizuno’s character as a brand, and while the JPX line is markedly different from the Pro offerings in materials and construction, the company goes to great lengths to leave their customers pleased.

Two bits of technology accomplish what the company is trying to do here. Acoustic Sound Ribs are positioned under the topline to reinforce the area and produce a solid impact sound. Harmonic Impact Technology presents itself in the form of a small, strategically placed bar that reduces sound pressure at impact. This has the effect of attenuating certain frequencies that produce the undesirable “high pitch” sound that many of us are unfortunately familiar with. It needs to be mentioned that there were some discussions about a grainy and shadowy video of the sound bar that were leaked on the internet prior to release, which even prompted some to compare the 925’s to a far less attractive iron from the past that had a large, black bar in the cavity. Mizuno, in our opinion at least, managed to incorporate this technology onto the iron in a way that blends nicely into the rest of the White Satin Brush finish many are so fond of. 

JPX925 Hot Metal Irons

Mizuno JPX Hot Metal irons cavity

The flagship iron in the JPX925 is the Hot Metal, which Mizuno describes as having “Maximum Speed and Max Consistency”. This iron, at least according to the chart halfway up the page, may not have a true peer when it comes to COR and CORAREA, and we expect the largest number of golfers will fit into them. Finished in White Satin Brush, light blue accents give the Hot Metal its own identity. Internet sleuths may notice a few changes in specifications from the JPX923 line, one of which we’ll talk about now. Slight loft changes of ½ a degree were made to four of the Hot Metal irons to catch up to the changes in performance realized by the new CORTECH face and Titanium weighting. This will ensure better gapping throughout the set. 

Both a matching GW and SW are available with Hot Metal irons, ensuring a uniform look and design. 

Lofts and specs of the JPX925 Hot Metal irons
  • Available 4-SW / RH and 4-SW / LH
  • Shafts: NS Pro 950 NEO & Recoil Dart ESX
  • Grip: Lamkin UT+
  • $150 per club

JPX925 Hot Metal Pro Irons

Mizuno JPX925 Hot Metal Pro irons

JPX925 Hot Metal Pro irons are built to offer almost the same level of performance in a smaller-sized iron head. Mizuno describes them as having “Maximum Speed” and a “Slimmer Profile”, which lines up with what we are seeing on paper and in person. This is a great option for the player that needs all the distance and most of the forgiveness that the Hot Metal offers, only in a slimmer profile. Again, we see some very slight changes to lofts of four irons, but we also wanted to discuss what appears to be a change in length in the JPX925 line. We asked the company about this, and it was easily explained. In reality, these irons are the exact same length as the 923’s, but Mizuno, after years of using a slightly different method of measurement, has aligned with the industry-standard method. In other words, the irons stayed the same, but the way they measured them changed. In addition, after much time analyzing data taken from Shot Optimizer 3D, the company has slightly tweaked their stock lie angles to better match what the majority of their customers need. Still, we implore you to take the time to get fit to maximize your purchase. 

The Hot Metal Pro irons are available with a matching GW in LH and RH. 

Lofts and specs of the Mizuno JPX925 Hot Metal Pro irons
  • Available 4-GW / RH and 4-GW / LH
  • Shaft: Dynamic Gold 105 & Mitsubishi MMT
  • Grip: Lamkin UTX+
  • $150 per club

JPX925 Hot Metal HL Irons

Mizuno JPX925 Hot Metal HL irons

Finally, the JPX925 Hot Metal HL irons exhibit Mizuno’s continuing commitment to finding the ideal fit for as many golfers as possible. The company is touting the HL irons as having “Maximum Speed and Maximum Height”. While the HL irons utilize all the same technologies in face design, multi-material construction, and sculpting sound, they are made so that those players that need more height are able to realize the most possible distance and accuracy (in the form of higher launch and spin). For some players, these irons will be true game changers, and we expect the HL line to continue growing in popularity over time. 

Lofts and SPecs of the Hot Metal HL
  • Available 4-SW / RH 
  • Shafts: Dynamic Gold 95 & Recoil Dart ESX
  • Grip: Lamkin UT+
  • $150 per club
  • For more information, make sure to check out their website at www.mizunogolf.com.

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Editor and writer Ryan Hawk lives in northwestern Illinois with his fiance and son. He's been a writer for The Hackers Paradise for two years and has been involved with a number of THP events.