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Mizuno’s JPX line of irons brings fast, futuristic, and balanced performance to the golf course. The JPX 900 family brought incredible success to Mizuno, including the highest market share they’ve ever achieved for an iron with the JPX 900 Hot Metal. It is that success that provided the springboard for the new JPX 919 line to outperform the competition. This year, Mizuno introduces the Tour, Forged and Hot Metal options with improved manufacturing processes and their industry-leading materials. TGW visited with Chris Voshall, Senior Club Engineer, to bring you the inside story of how these irons came to life.

JPX 919 Tour

“The 919 Tour’s compact profile doesn’t tell the whole story – there’s a surprising level of stability and distance control built into this geometry. Its predecessor attracted a new wave of younger tour players into Mizuno irons – making a big impact winning back-to-back US Opens and recording a course record 61 at St Andrews.” – Jeff Cook, PGA Tour Manager

Thanks to a new stable of pro golfers to provide feedback, the JPX 919 Tour irons are a more compact, streamlined evolution of Mizuno’s standout tour iron. “The feedback we heard was that they [JPX 900 Tour irons] felt a little bit firmer and the top line was a little bit thick,” said Chris Voshall.

The 919 version is compact and lean-looking down by the ball. This profile satisfies the eye of elite-level shot makers. A tour grind top edge narrowed the top line by 10% in order to fulfill the request most players were making.

For the first time in the JPX line, Mizuno is using their Grain Flow Forged HD process. They start with a single billet of 1025E pure mild carbon steel that provides that signature feel. This process compacts more grain into the impact area for more vibrations. Vibration is what provides feedback on shots. The idea is to maximize feedback but tune the vibration to the proper frequency so it feels perfect.

Finally, there is the new stability frame design. Mizuno took weight out of the heel and pushed it out low on the toe. This helps fine-tune the frequencies of vibration for that tour-preferred feel and sound. “This also brings the sweet spot closer to the center of the club face and brings the center of gravity deeper, improving launch and lowering spin just a tad,” Voshall told us.

JPX 919 Forged

“A deeper, wider milling across the back of the face makes the JPX 919 Forged able to transfer more energy to the ball than any previous Grain Flow Forged irons. None of that would have been possible without the small addition of boron into our steel billets,which gives the additional strength needed to reinforce the face.” – David Llewellyn, Director of Golf R&D

The JPX 919 Forged irons are Mizuno’s most versatile. Whether it’s a tour player looking for a little distance boost or an amateur wanting to evolve their game with more feedback, the Forged offering has something for golfers at every level. This is made possible by using a slightly different material than in the Tour irons. The Forged irons are made from 1025B carbon steel which has just a trace amount of Boron. That small amount of Boron makes the steel billet 30% stronger, allowing for greater design possibilities through the forging process.

Mizuno still used their Grain Flow Forged HD process on these irons. They also include the stability frame design. But this option was missing something. “This line needed some more work. We needed to rework the weighting and maximize COR,” commented Voshall.

So they developed a reverse-milling process for the club face. These clubs are CNC milled from the sole up to create the thinnest possible face. By extending the thinness of the face to more locations, Mizuno increased ball speeds consistently all over the face. The weight that was removed by the process creates a lower, deeper center of gravity for easier launch in the long and mid irons. “By measured ball speeds, these are the fastest-ever forged irons we have ever made,” Voshall remarked.

JPX 919 Hot Metal

“The most important thing about the JPX 919 Hot Metal is the launch control and flight apex – the extra ball speed and distance doesn’t come from low flying bullets. We work the design backward from the correct landing angles. These are irons for the golf course, not just the launch monitor.” – Chris Voshall, Senior Club Engineer

Mizuno’s Hot Metal irons are packed with all the distance benefits you could want in a package that looks like a Mizuno iron. If you want to hit it far and high with an incredible launch angle, this is the JPX 919 iron choice for you.

These clubs are made from a unique material called Chromoly 4140M. It is 15% stronger for a metal toughness and offers some versatility. Chromoly helps create the thinnest face possible for faster ball speed but keeps the hosel bendable for customization. “We can heat treat parts to add strength while also making it more bendable where you need it,” explained Voshall.

Just like the rest of the 919 irons family, the Hot Metal irons feature the stability frame to enhance launch and loft. There are also re-engineered sound ribs developed to maintain the specific vibration patterns for a more satisfying feeling when you strike the golf ball.

The cup face of the club is also cast as a single piece so there is no added weight or inconsistencies with welding multiple pieces together. This extends the thinnest parts of the club face to more areas, expanding the area where you get that trampoline effect to launch the ball farther, higher, and faster. With all those distance benefits, these clubs are still extremely playable. “We needed to provide the proper launch and proper spin to play on the golf course, not the launch monitors,” said Voshall.

Which One Is Right For You?

JPX 919 Tour – Ideal for the better golfer, made for maximum control and workability
JPX 919 Forged – Ideal for most golfers, these irons have something for everyone with feel and control as well as distance and forgiveness benefits
JPX 919 Hot Metal – Ideal for golfers who need distance and launch help, loaded with maximum distance benefits in a package that looks like a signature Mizuno iron

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