Mizuno Pro S-4 Irons Review: Feel, finesse and (just a little) forgiveness

It's hard to improve on complete purity, but that's the rod Mizuno has built for its own back.

The Mizuno Pro S-3 irons are regarded as some of the cleanest money can buy, with a sleek players' profile and an uber-clean cavity back structure adding a touch of forgiveness to the overall package. As such, the S-3 is one of the most popular Mizuno iron models on tour and among better players.

Now, the latest entry into the Mizuno Pro has made its appearance in the form of the S-4, which perhaps predictably replaces the S-3 as the more forgiving, cavity-backed alternative to the bladed S-1 (or soon to be S-2, if the rumours are to be believed).

This, of course, is an interesting proposition given Mizuno's most recent releases. The latest editions in the Pro line, namely the M-13 and M-15, are also designed to fill that gap between the traditional player's iron profile and a more forgiving players' distance iron.

Who, then, is the S-4 for, and does it do the job? We took a set out on the course to find out.

Check out our video review below and scroll on to read our detailed thoughts. Let us know what you think of the new Mizuno S-4 irons in the comments below.

Looks and features

To start, let's drill down into exactly what the S-4 is for, and how it sits in Mizuno's revamped Pro line-up. 

While it may be a little confusing to hear that the S-4 is designed to be a more forgiving alternative to the S-1, according to Mizuno's own iron comparison tool, it sits pretty much flush between the S-1, which is the slimmest, most compact Mizuno iron of all, and the M-13 and M-15, which err closer and closer the Players Distance category. 

The S-4, then, is still more compact than the M-13, with a slightly shorter blade length and less sole width, but more offset towards the longer end of the bag to address this. As such, it presents a very slim package at address, with a thinner top-line compared to, say, a Titleist T100.

Perhaps more importantly, the S-4 is both wider and equipped with significantly more offset than the S-3, with more mass concentrated lower in the head to deliver increased forgiveness, higher launch and greater stability.

This, in theory should make it a more forgiving foil to the S-1 when used in a combo set. Think of it as the T150 to the S-1's T100.

All of this goes without saying that Mizuno haven't done heaps outside of the reshaping to upset the apple cart with the S-4 range. It's still made using the same Grain Flow Forged HD process as other Mizuno irons, hewn as always from a single billet of 1025E Mild Carbon Steel.

It also has the same copper underlay and harmonic tuning as the M-13 and M-15 ranges, delivering even more refinement to that classic Mizuno feel. Even so, this is a pretty simple golf club, with none of the hidden tech that these clubs store away to aid forgiveness.

Looks wise, it's as pretty as any other Mizuno Pro iron of recent times, which is to say extremely.

What we like

Mizuno's legendary reputation for feel remains warranted with the S-4, and the irons once again deliver all the purity that we've come to expect from the brand. Interestingly, they're not quite as soft as some other irons from the likes of Titleist and Srixon, rather we'd define the feel of the Mizunos as solid and refined, with lots of feedback retained to give better players an idea of when they haven't struck it quite right. 

We found this slight added firmness was amplified further when used by a higher swing speed player, but they're by no means clicky, and players wanting that classic Mizuno sensation at impact will find lots to love here.

The major question with the S-4 is whether or not these forgiveness-oriented tweaks make a tangible difference for players who maybe aren't playing at their best on any given day, and we'd say they do. 

The S-4s still operate on a very fine line between hitting a pure shot and missing it, but we found the drop-off in spin and distance on less ideal strikes wasn't quite as harsh as in other players irons we've tested, and they still delivered pretty consistent results when we tried to push them further and further into striking off the toe or the heel of the club.

What we don't like

There's not a lot to address here, however it's worth reiterating that while Mizuno have added some forgiveness into the S-4's overall package, these remain very much a players iron in feel and nature. If you go into testing these clubs expecting an experience geared towards a mid-handicapper, you're going to be disappointed.

As we mentioned, the Pro S-4s present a pretty small package at address, even compared to other players irons in its class. 

This may well suit players of a more traditional mindset, but for those who have become accustomed to having slightly more club behind the ball, the S-4s might look a little bit hard to hit if these are your first proper players irons.

There's also the small variable of offset. The S-4s carry more than not just any other Mizuno Pro iron , but also the JPX Hot Metal Pro and Forged models. This might not suit players who already struggle with missing their irons left.

Should you buy the Mizuno Pro S-4 irons?

We've established that, as we expected, the Mizuno Pro S-4s are very, very good irons. Who, then, are they for?

Make no mistake about it, these are still irons that ask something of the player if they're have a chance of getting the most out of them. 

The compact nature of these irons, along with their simple build, requires use by a player with better ball-striking and face control, and we wouldn't really recommend them unless you were playing from at least a mid-high single figure handicap. Those lower-mid handicappers who want an iron that more successfully bridges the gap between the players and players distance categories should instead look at the M-13.

What S-4 players will get, however, is an iron with even more feel and finesse than its predecessor, and just a touch of added forgiveness to help you attain that legendary Mizuno performance even more often if you already strike the ball with confidence and consistency. If you fit this profile, you'll likely find the Pro S-4s hard to fault.