Persimmon Woods conforming in tournament play?

Just out of curiosity - does the R&A or USGA exclude clubs that are non-conforming (and therefor allow all other clubs you can buy) or do they specify which clubs are conforming?
So in general - are Persimmon Woods conforming - and if yes, have there been non conforming Persimmon woods in the past? Is there actually a design feature in a persimmon club that could make it non-conforming? I guess shaft length/trampolin effect/head size arent real issues here?

Maybe some of you read the discussion about Mickelson during the beginning of the year where he played a Ping wedge that had the non conforming grooves but wasnt labeled as non-conforming. Is this an issue with old iron sets/wedges (+20years or older) or have most of them conforming grooves in them?


I can’t imagine you’ll come across any persimmon wood that would be deemed non-conforming. 460CC heads were unheard of in the days of persimmon as was “COR”. Unless someone was designing a persimmon driver with a shaft that entered the head at a really funky angle (like thru the sweetspot) my guess is that all persimmon heads are conforming.

The square groove thing (Mickelson was using a club that was essentially considered “illegal” but which had been grand-fathered in as legal as part of the lawsuit Ping brought back in the day regarding the groove designs they were using … I may not have it totally accurate but it’s something along those lines). “Most” iron designs over 20 y/o conform, but the USGA has a website that is “supposed” to let you know if a particular set is legal or not. Unfortunately, the USGA has the most incomplete list in the history of lists. The last time I checked it the majority of iron designs I checked on fell into the category of “atr”… additional testing required.

btw… I understand from reliable sources that for a club to pass the driver COR test it can “fail” the test more than once. As long as it “passes” one time it’s considered legal. I wonder how may drivers on tour actually failed the COR testing at some point??? My guess is all of them.


I was reading up on some stuff when i came across an article of 2003 (long before i ever touched a club) - where Tiger complained about the use of “hot drivers” by his competitors. So i guess when these guys go shopping around for a driver head they will test it and choose the one that maxes out the limits? ( …

Regarding these iron sets - what would have happend when Lag would have played an “ATR”-set of irons, qualified for the Open but his compeptitors didnt like it, and told on him? Would he had to have this set sent to the USGA for testing to clarifiy if it conforms or not?


I doubt any tour pro has to “shop around” for his next driver. My guess is that each manufacturer is loaded with “conforming heads” that they gladly put together for anyone on staff. I would also bet that lots of those “conforming” heads make it to the Big Box stores as “Demos”… (try buying a “demo driver” from one of your local retail golf stores… it can be more difficult than you might think).

If someone just got his ass handed to him by Lag in a US Open qualifier using a set of Mac M85’s and was man enough to request a conforming equipment check then yes, he’d probably have to send them into the USGA for groove testing lest it showed up on their list, which it won’t. Square groove checks aren’t quite as simple as one might think. My understanding is that they have to make a “male” mold of the face and then check that to determine if the grooves conform.


Yes, they dont walk into Golfsmith and try them out of course :laughing: . There was this story about Mickelson´s driver where the head took damage right before the Masters. Despite having a backup driver with the same specs, he instisted that they would repair his driver because he felt that the face was “hotter” than his backup driver. So they took it to the lab - dismanteled the face from the head and built a new head around the face. I mean superstition just goes so far, and if Mickelson insists on keeping the driver face (despite spraying it all over the place) he might just realize that his “gamer” compared to his backup might just be a “bit more conforming” than his other club…

I actually tried this, but unless its after season sale, no chance. But then again, the last driver i bought was 3 years ago, just standard of the rack, and its a great club - i guess i just got lucky this time…