Mizuno JPX921 Hot Metal Irons Review

50 Words or Less

The Mizuno JPX921 Hot Metal irons are long and fairly forgiving.  Better feel than previous generations.


Mizuno has hit on a winning concept with their Hot Metal line.  For the last several generations, more and more mid to high handicap players are switching to this “players” brand because the Hot Metal allows them to.  I tested the new JPX921 Hot Metal irons to see if this trend will continue and to find out what’s new about Chromoly 4140M.


I believe that a lot of the appeal of the JPX921 Hot Metal irons, as with their predecessors, comes from the way they look in the bag.  Mizuno ditched the bright colors often associated with game improvement irons and opted for silver and black.  The mix of chrome and matte finishes gives them some flair, but, at a glance, they look like players irons.

At address, the JPX921 Hot Metal is clearly a game improvement iron, verging on super game improvement.  It has the largest head, thickest top line, most offset, and widest sole of any current Mizuno iron.  All that said, Mizuno did a nice job shaping the offset so it’s not jarring, and they used a two-tone top line to make it appear slimmer.

Sound & Feel

Both the JPX921 Hot Metal and the JPX921 Hot Metal Pro irons are made with the same Chromoly metal and feature a frighteningly thin face.  These irons feel very crisp on center but are much quieter than previous iterations.  Neither iron feels soft, but pure strikes do feel solid.

Feedback is about what you’d expect from a game improvement iron.  Misses get dull, losing the crisp snap.  Through the hands, feedback isn’t precise but it’s good enough to get a general idea about how you struck the ball.


If you’re familiar with the Hot Metal series, this section will contain exactly zero surprises.  The JPX921 Hot Metal irons do exactly what their predecessors have done: create lots of ball speed with a decent amount of forgiveness.

Let’s get more specific about forgiveness.  What the JPX921 Hot Metal irons do very well is maintain ball speed.  That means that you can hit a toe or heel shot and it will still fly fast and far.  However, if your primary issue is hitting thin shots, I think the Hot Metal is ordinary for its size.  Thin shots are going to fly very low and run like crazy.

Speaking of running like crazy, the JPX 921 Hot Metal irons, just like the Hot Metal Pro [review HERE], are fairly low launching and low spinning.  This is, in large part, because of the very strong lofts.  If you tend to hit high, spinny shots, these irons will be great.  If you struggle to hold greens, I would look elsewhere.

Finally, credit to Mizuno for making the Hot Metal and Hot Metal Pro irons easy to mix in a combo set.  Both sets share specs from loft to lie to length, so you can easily play the Hot Metal long irons and Hot Metal Pro short irons.  The Hot Metal Pro has a shorter heel-to-toe length and substantially less offset, which are desirable traits in the short irons for some players.


The Mizuno JPX921 Hot Metal irons continue to be a fine choice for the mid to high handicap player who wants distance but needs to play a Mizuno.  There are no quantum leaps forward from previous versions, so if you’re happy with your current Hot Metals, there is no need to upgrade.  The ability to easily combo these with the Hot Metal Pros is a real benefit.

Mizuno JPX921 Hot Metal Irons Price & Specs

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Matt Saternus

Founder, Editor In Chief at PluggedInGolf.com
Matt is the Founder and Editor in Chief of Plugged In Golf. He's worked in nearly every job in the golf industry from club fitting to instruction to writing and speaking. Matt lives in the northwest suburbs of Chicago with his wife and two daughters.

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  1. Great Review Matt. How would you compare the JPX Hot Metal to the T400 irons you recently reviewed in terms of distance, playability and forgiveness. Keep up the great reviews. Thanks.

    • Matt Saternus


      Based on memory, not head to head testing, the distance and forgiveness of the T400 is better.


  2. Alfred Millon

    I have recently struggling to find irons that I love to play golf with.. It reminds me of the first big bertha driver when it came out,, just loved it and hit good most of the time.. I tried the mavrik, M5, and pings 700…. I have made a decision that these Mizuno JP 921 IRONS ARE BETTER THAN All the ones mentioned… I’ve played 4 rounds with them and find the very solid and hold the greens just fine..

  3. Why is there no 3 iron available? Not everyone likes hybrids! I have purchased my last two sets from Mizuno and like them, but it is frustrating to have to have my old ping eye 5, 2 iron in the bag ????

  4. Donald fregin

    Would the cost be worth the money over my Mizuno 850s

    • Matt Saternus


      Barring a major improvement in the way they fit you, I doubt you would see a major change in performance.



  5. Great review Matt, but for us lefties the ‘advantage’ of a combo set does not apply. Worth mentioning?

  6. For John, Ping Eye 5 2i loft is 18° and the Mizuno Hot Metal 4i is 19° therefore no need for a 3i.

  7. I notice that the stock shaft is the new 950 Neo. Did you demo the club with the Neo and ,if so, what are your thoughts regarding the pairing?

  8. Look y’all, these irons are FANTASTIC. I am a scratch player, hit irons pretty well, but have been going through iron sets like underwear lately trying to find a head/shaft combo that I love. I found it. I got the 919 Hot Metal Pro this summer (with KBS C-Taper Lite Stiff for me) I’ve been losing distance- these helped. I spin it a bit too much- these helped. My miss is toe side – these helped. I dig too much – the soles helped. I thought I may lose consistency of distances without a forged iron….. nope. Love them. The only “negative” would be that the loft spread makes for a few yards wider gap between clubs. And to the question of why there is no 3 iron…. dude, look at the lofts. The 4 iron is 19 degrees… similar to most 3 irons. I hit it almost as far as my 19 Hybrid (and mush straighter) so I no longer need the hybrid in the bag. Use that spot in the bag for a driving iron, or 5 wood, or another wedge.

  9. Dadwholuvsgolf

    I have been playing 921 Hot Metal for a month now. What a great long set of irons. Love the feel and distance. If you want a long set and a set that goes high and lands soft buy these irons. You won’t be disappointed.

  10. Thanks for the review. I have had my eye on these since they have come out. I have also looked at the Cleveland Launcher UHX Irons. How would you compare the two sets? I am looking for something that is forgiving and easy to hit.

  11. Matt,
    Within your remarks you suggested that this might not be a good choice for golfers who may tend toward thin shots. Which irons would you recommend to minimize that tendency?

    Thanks, tpm

    • Matt Saternus


      To be clear, no iron will minimize your tendency to hit thin shots, but there are irons that will turn thin strikes into decent results. I would suggest looking for an iron with a wider sole and, ideally, lofts that aren’t as strong.



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