Cobra King F6 Irons Review & Interview

The return of the KING moniker from Cobra has also brought with it an increased emphasis from the company for thinking outside of the box. The LTD metalwoods were the first example of this and now in the realm of irons Cobra is going all in with their KING F6. These are a completely different take on the progressive iron set and utilize a plethora of construction and design techniques combined to create what could be one of the most versatile and dynamic irons ever from the company.

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Cobra on the KING F6 Irons:

The KING of Progressive Iron sets. Optimum performance is achieved through advanced construction techniques. The result is an iron designed to create more feel, distance, precision and forgiveness.

  • TECFLO CONSTRUCTION – Multiple construction technologies flow together to create the ultimate progressive irons. Each club in the set is designed to perform differently, optimized for performance to help golfers hit more greens and hit it closer to the pin.
  • SPEED CHANNEL SOLE – An engineered channel positioned on the sole, close to the leading edge of the iron and around the perimeter of the upper back cavity, creates more flex at impact to deliver greater distance through faster ball speeds.
  • PREMIUM CHROME PLATING – A new nickel chrome plating combined with a gunmetal PVD coating provides enhanced durability and a confidence inspiring aesthetic look at address.
  • T.O.P. TECHNOLOGY – An engineered aluminum cap replaces steel on dual cavity hollow irons which frees up 5g of discretionary weight which has been placed low and further back in the head creating a lower CG position for improved launch conditions and ball flight.
  • PROGRESSIVE SPIN TECH – F6 Irons come equipped with V-Grooves on 4-6 irons to reduce spin, U-Grooves on the 7-PW to optimize spin, and Wedge spaced grooves on the GW-SW to produce extra spin for shots around the green.
  • DEEP PERIMETER UNDERCUTTING – An extremely deep undercut creates the largest unsupported face ever in a COBRA set of irons, meaning you get extreme distance on center hits and consistent forgiving distance on off-center hits.
  • CNC MILLED GROOVES – CNC Milled Grooves increase spin and optimize trajectory throughout the set. This provides improved control and workability giving you added confidence when you’re attacking the Pin.


Iron Loft Lie Offset
Graphite Swing
Steel Swing
3 18° 60° 5.5 40.25″ 40.00″ D0 D1 RH/LH
4 20° 61° 5.5 39.50″ 39.25″ D0 D1 RH/LH
5 23° 61.5° 5.0 38.75″ 38.50″ D0 D1 RH/LH
6 26° 62° 4.5 38.00″ 37.75″ D0 D1 RH/LH
7 30° 62.5° 4.0 37.50″ 37.25″ D0 D1 RH/LH
8 35° 63° 3.5 37.00″ 36.75″ D0 D1 RH/LH
9 40° 63.5° 3.0 36.50″ 36.25″ D0 D1 RH/LH
PW 45° 64° 2.5 36.25″ 36.00″ D1 D2 RH/LH
GW 50° 64° 1.0 36.00″ 35.75″ D1 D2 RH/LH
SW 55° 64° 0.8 35.75″ 35.50″ D2 D3 RH/LH


Model Flex Weight Kick Point Torque Tip Diameter
KING F6 Iron Graphite / Matrix Red Tie 65Q4 S 66g Mid-Low Mid 0.370
KING F6 Iron Graphite / Matrix Red Tie 65Q4 R 63g Mid-Low Mid 0.370
KING F6 Iron Graphite / Matrix Red Tie 65Q4 A 62g Mid-Low Mid 0.370
KING F6 Iron Steel / FST Steel Flighted S 100+g Mid Mid .370
KING F6 Iron Steel / FST Steel Flighted R 100+g Mid Mid .370


Interview with Cobra’s Tom Olsavsky about the F6 Irons:

Because of the outside the box nature of the F6 irons, THP had a discussion with Cobra Golf’s VP of R&D Tom Olsavsky about several different aspects of what make the set so unique:

THP: Progressive irons are not a new concept, but what we are seeing with the F6 irons is something totally different on that front with four different design technologies, what is the reasoning for this? 

T.O.: This reasoning was based on research for what players want in a set of irons. Since a normal set covers a wide range of distance/consistency shot needs, we re-thought the conventional way that irons were designed.  Most players will freely admit that they want easier to hit long and mid irons and more precise short irons and wedges. Therefore by looking at each iron and the role it plays, the path from this feedback was fairly straightforward for the KING F6 irons with FLOTEC.

THP: The FLOTEC design ideology is as well rounded as we have seen before, it could be argued that each of the four head designs within the F6 could be their own set, how did you decide the optimal “FLO” for each head and where they should start/end within the set?

T.O.: Similar to the response above, we let the golfer feedback drive the needs for CG placement, Inertia and other playability specifications. There is also some conventional size and shape constraints that golfers are comfortable with so we combined all these elements into the FLOTEC concept.

THP: The hollow irons (4, 5) in particular have a LOT of tech in them with the use of aluminum in the design, what has this allowed you to do and why was aluminum the choice in an iron design?

T.O.: We are continually looking at the structure and materials of every clubhead that we design. Aluminum is a great material for light weight while providing very good strength as its’ widespread use in aircraft clearly shows. In golf it is much less popular since we have a very high impact requirement. However, it works nicely in the back of the KING F6 irons since the steel face and sole take the impact, while the aluminum is used to lighten the top of the head for better performance. It is a nice Win-Win scenario for long and mid irons where the weight savings go directly into lower CG and improved performance.

THP: Another interesting feature of the F6’s that is outside the box of what we have seen is with the grooves in the irons. Although other sets have adjusted the grooves (amount/spacing) with these you have actually utilized different groove types through the set, what does this allow you to accomplish and how did this idea come to be?

T.O.: In our constant challenge to bring golfers more distance, while maintaining ease of use and playability, we left no stone unturned it producing the best irons we can with the KING F6 set. By using V-groove in the 3-6 irons, we were able to produce a couple more yards per clubs vs a U-groove. This reduces spin about 200 rpm (on the 6 iron), which produces 2.5 more yards carry, while only rolling out 1.5 feet more on the green.  We think this is a great benefit to what golfers want, more flight distance, but also maintaining control on landing.

THP: Although the stock shafts play significantly on the lightweight/flighted trend as well, Cobra is also offering a lot of popular heavier weight options at no upcharge. With that in mind, who do you view as the target audience with this set, is it one that can run the gamut?

T.O.: We believe the KING F6 iron is best positioned for typical amateur that ranges from 5-6 handicap up to the 25-30 handicap range. For the higher ranges, we offer the Cobra MAX line we is even easier to hit and more forgiving than the KING F6.

THP: What do you see the F6 Irons accomplishing for Cobra within the iron realm?

T.O.: I am very pleased with the Cobra KING F6 irons, from all aspects of performance, looks/feel and positioning. We expect them to sell well and provide golfers with a great new set of irons that answers their performance needs and brings more FUN to their golf games.


We all know Cobra has never been afraid to push boundaries when it comes to the aesthetics of their clubs, the F6 irons do this both in looks and design. From a design standpoint, we have never seen a progressive iron set quite like this, rather than a simple adjusting (offset, sole width, slots) throughout, Cobra has built four unique iron designs into one set. The set is made up of full-hollow, half-hollow, cavity back, and muscle back construction and each one could in their own right be turned into an entire set.

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All of the irons feature a nickel chrome and gun-metal PVD finish/plating that over the time of the review has worn quite well. Sure, they do mark up some on the face, but any dark finish will do this to some extent and these hold up there better than many dark finishes we have seen. However, rather than trying to make all the different design-types in the set look the same, the finish and badging varies throughout each of the four shapes/designs. While this is initially a bit confusing because we are trained for a look that is the same throughout a set, it works well for highlighting the story of the set, which is most definitely the technology.

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THP was sent the KING F6 irons for review in the 4-GW configuration paired with the stiff-flex Matrix Q4 Red-Tie graphite shafts. All testing was done on the course, range, as well as a launch monitor.

  • Sound/Feel

This area is likely to be one of much conversation/concern considering the material and makeup of the set. On the material side you will undoubtedly have those who point out that these are not forged and also feature things like aluminum in the design of the long irons which is definitely outside of the “norm”. From a makeup outlook the focus will fall on the hollow and half-hollow irons as when we have seen this design trait from other companies there have been issues with them feeling/sounding hollow. All of that can be put to rest with the KING F6 irons though as Cobra has managed to not only create good sound but also get four designs to meld pretty seamlessly.

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The irons are definitely on the firm end of things, but they avoid the trap of being too “clicky” or “hollow” and a lot of that comes back to the badging/dampening variances through the set. This feedback gets a bit sharper lower on the face, but even then on most misses it isn’t extreme. Across the faces, everything feels very similar from center to toe/heel and while that may not be what the hardcore forged users of the world want in terms of feedback, for a progressive GI set like this makes the irons even more playable from a “feel” perspective.

  • Launch/Spin

The KING F6 irons are a design concept that takes a lot to get ones head around thanks to having so many different aspects. Because of that it will be easiest to break down this category based on the design type.

o   Full-Hollow (3/4/5)

o   The full-hollow portion of the TECFLO iron design is obviously the biggest in terms of topline/offset but the real intrigue comes with the hollow body and use of aluminum. This reviewer is one who does typically have issues with height on long irons but the combination of the full hollow design as well as the Red-Tie shaft pairing found peak heights of 32 and 33 yards (average) were seen from the 4i/5i during testing. Moreover, the spin stayed impressively low considering, which is due to both body design and the use of V-Grooves. That said, thanks to that high peak they also had no issues holding greens thanks to the descent angle. Yes, there was some run-out, but much less than the lower flighted (comparatively) long irons that have been tested as of late. Additionally, for those who may point at the shaft pairing as the main cause of this ball flight, these were also tested with 130g steel and similar higher launching and lower spinning results were seen. It is a design that just works, and the performance will hopefully trump the aesthetic concerns which some may have.

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o   Half-Hollow (6/7)

o   The Half Hollow irons offered a slightly higher launch and peak height (average of 34.5 yards) from the full hollow irons. With these irons, the real intrigue comes with the spin seen during the testing. In the half hollow irons the 6i features the same V-Grooves as the 4i and 5i while the 7i instead has U-Grooves to optimize spin in the irons which are most often hit into the greens. Data recorded did show a difference in spin when hitting the 6i next to the 7i, likewise for this reviewer the 7i is the starting point where golf-ball action could be seen when hitting the green. While it may be something that could be easily overlooked in terms of information about the design, it was impressive to actually see the difference the groove change made on the golf course.

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o   Cavity Back (8/9/PW)

o   The Cavity back irons saw the highest launch of all design segments of the F6 set. However, though the data definitely places them in the “high” ball-flight segment, it is not as drastic of a jump as seen in some other sets thanks the sequence of the set. Spin numbers did increase and as these are definitely considered the scoring irons it should be expected. Also worth noting here however that the irons maintained what could/should still be considered a higher ball flight even when moved to “tour weight” shafts and stronger flex. The fact of the matter is the head designs work, and work well.

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o   Muscle Back (GW/SW)

o   The set GW is definitely fitting of the Muscle Back moniker which it carries on the badging and is akin to what we have seen some other sets in this classification. The ball flight was pretty much on par with that of the PW but did have the notable spin increase which you would expect from a bladed design. Part of that also comes back to not only featuring the same U-Grooves as the 7-PW of the set, but also more “wedge spaced grooves” as Cobra says which provide for more potential on greenside shots as well as swings from the fairway.

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  • Distance/Forgiveness

Distances recorded with the KING F6 irons were surprisingly long, playing longer than the Fly-Z/Bio-Cell before them and were easily among the longest irons this reviewer has ever tested. Not only does it come back to launch and spin, but the ball speed generation and retention of the faces particularly in the Full Hollow and Half Hollow irons is borderline staggering. While some may point out the lightweight graphite shaft which was tested as being a key producer of the numbers seen during review, the set was also shafted up with 130g flighted shafts and there was very little change in the data. Another concern of some could be the gapping of the set, however there was no significant gap where the tech changes as we have seen with the common two part progressive sets. By having four distinct designs within the set, the gaps remained consistent and better yet, predictable. The fact of the matter is that the tech in the heads is legit, and with a proper fitting there is a lot of potential.

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As impressive as the set is on distance and ball-speed generation, the retention of that speed across the faces is equally as such. Thanks to the four-part design the CG is manipulated through the set where the majority of us need it the most, including the use of aluminum in an iron design (Full Hollow and Half Hollow) which is yet another example of the innovation in the set. Add to the shape/structure differences, the set also features the deepest perimeter undercut which Cobra has produced and the recipe for “forgiveness” is there. Results on misses low, high, and toe side were among the best this reviewer has seen, particularly in the 4-7 irons. Though as mentioned in the sound/feel section the impact point of the irons is a bit blurred across the face, this only added to the surprise when looking at the ball mark to see just where on the face impact was made. The ability of the irons to maintain height as well as a manageable level of spin change kept shots in play and on line much more than expected as well.

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Parting Thoughts:

Most of the emphasis from Cobra recently has decidedly been on the metal-wood side of things when it comes to what most will perceive as unbound innovation. This isn’t to say that there hasn’t been a lot of effort and research put into their iron releases, but this year it is evident that something has changed. The F6 irons are without any doubt the most innovative iron release we have seen from the company and though the idea of a progressive set is not new the F6 are progressive in so many ways that they are incredibly different from what we “know” as consumers. More importantly, they are a design that works and works well. These are the first irons in a long time from Cobra for which it can be said they are definitely worth a look.

The KING F6 irons are priced at $799.00 for the 8-club 4-GW configuration and more information on them and the entire KING line can be found at

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James Miles
James is a staff writer for The Hackers Paradise along with being a professional educator. With his background in education James seeks to broaden his own knowledge while also sharing it with all those who share his passion for the game.
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