The Mizuno JPX850 irons are all about distance with feel and whilst Mizuno say they are not going to shout about the distance aspect of the JPX850, it really is the main story.
The Power Frame that makes up the chassis of the head is larger to increase the area that the thinner face can stretch across. This in turn increases the Coefficient of Restitution (COR) or spring like effect of the face to levels Mizuno say make them faster than the legal limit on drivers, which apparently is within the rules.
I put the JPX850 up against the previous Mizuno JPX825 iron on a launch monitor and the ball speed was around 1-2 mph faster with the new version, which is good for slow swing speed players needing to gain a few yards.
In irons distance needs to be consistent between clubs and not to create gaps between the irons and the wedges or woods. On this front the JPX850 irons were very good with consistent distance right across the face and no hot spots in the centre where you could get one jumping.
The feel was pretty good for a cast iron and the sound at impact was similar to the JPX825, so if you liked the slightly clicky sound before, then you will like these too.
As well as new graphics on the blue cavity badge, the other main visual change is the sole where the camber grind on the previous model has been replaced with a cut-away 'Dual Relief Zone' style to make the sole play a little narrower and the function wins over form for me here.
The brushed steel look continues into the cavity to replace the black finish of the JPX825 and overall I think it does look cleaner and more like what you would expect from a Mizuno iron than before.
All this extra weight pushed back and the addtional speed gave a nice high flight, so if you struggle to get your irons up in the air then these will be perfect for you.
They will also be confidence inspiring as the the thick top lines and generous head size frame the ball at address ready for you to launch at them. I do like this sort of large head size in a mid-handicapper iron and Mizuno has balanced the need for size without getting too chunky.
The standard steel shaft is True Temper XP105 that is 27 grams lighter than a Dynamic Gold in the regular flex and this is ideal for this type of club. It has all the rigidity you need, but the lighter weight is easier to manage and will enable slower swing speed players to generate more clubhead speed.
Overall I think Mizuno has improved the JPX850 iron on the previous model as it looks sharper and goes faster so that will help make it more playable.
There are a lot of high forgiveness 'player' irons in the market and the JPX850 is a very complete package. If am being very picky, the sound and feel are up against strong competition in this sector and they are a touch behind one or two other models we have tested, hence why it is getting 4 stars and not 5.
That said, the JPX850 are ideal for mid handicaps who prefer the look of a larger more forgiving head that does not have a large offset on the hosel. These could be ex-low handicappers on their way up, or aspiring players on their way down who want to be seen playing a Mizuno and that is a good enough reason to choose them.