In a statement released Monday, McCarron discussed his original comments to the San Francisco Chronicle regarding Mickelson and other players using Ping-Eye 2 clubs that have grooves which no longer conform to USGA and PGA Tour standards, but are still considered legal because they were grandfathered in two decades ago.
"I responded, 'It's cheating and I am appalled Phil has put it in play,'" McCarron stated. "I never called Phil Mickelson a cheater. That being said, I want my fans, sponsors, and most importantly, my fellow players, to know that I will not be silenced and I will continue my efforts to get the groove issue resolved."
Interviewed by CBS during its telecast of the third round of the Farmers Insurance Open on Saturday, Mickelson maintained that he had been "publicly slandered" by McCarron. He later addressed the situation further, saying, "Again, everybody has their opinions and so forth, and it's healthy to talk about it. But when you cross that line and slander someone publicly, that's when the tour needs to step in -- or someone else."
For its part, the PGA Tour has stepped in, issuing a statement that read, in part, "Because the use of pre-1990 Ping-Eye 2 irons is permitted for play, public comments or criticisms characterizing their use as a violation of the rules of golf as promulgated by the USGA are inappropriate at best."
There will be a player meeting on Tuesday at Riviera Country Club, site of this week's Northern Trust Open, during which this topic is expected to be discussed.
"The USGA and the PGA Tour were made aware of this potential issue by its players last year," McCarron added. "Instead of acting or addressing the matter, the tour chose to put the onus to comply on its players. Unfortunately, a handful of players have chosen not to comply and that is what has led to this current ordeal.
"In my opinion, as a 16-year veteran of the PGA Tour and a member of the tour's Player Advisory Council, the tour must now put a rule in place to protect the field and ban these wedges," he said. "Most of the players on the PGA Tour feel the loophole in this rule needs to be closed."
Square grooves no longer are allowed on the PGA Tour because of a new USGA policy effective this year that requires grooves in irons to be a more shallow V-shape, which generates less spin.
However, the Ping-Eye 2 wedges made before April 1, 1990, are approved for competition because of a lawsuit that Ping settled with the PGA Tour and USGA some 20 years ago.
It has not been proved whether the grooves of a 20-year-old golf club -- Mickelson played them in college at Arizona State and found this wedge in his garage -- spin more than V-shaped grooves made with today's technology.
Ping chairman John Solheim said Monday the PGA Tour is bound by a 1993 settlement that says the tour cannot create a special rule that differs from the USGA. The Ping chairman, however, says he's willing to discuss a solution.
While McCarron has been the most vocal adversary of this decision, others have echoed his sentiments.
"I think cheating is not the right word to use," Robert Allenby said. "But it's definitely an advantage. ... I just believe that even if they are legal, you shouldn't be using them. Just because someone has a couple sitting in their garage somewhere or they've got them off eBay or wherever. I just don't think that's the integrity of the game."
The issue is also gaining traction overseas. Speaking from Qatar, where he was competing in a European Tour event, fourth-ranked Lee Westwood told reporters, "As one of our premier players, [Mickelson] should be one of the guys who steps up and says this is wrong.
"It's a very strong word to use, cheating. It wouldn't be my choice to use them, but it's obviously not against the rules or else he wouldn't do it," Westwood said. "I could do it more than anybody else because I've got thousands of Ping wedges. I have the opportunity to do it and I don't."
Jason Sobel is a golf writer for ESPN.com. Information from The Associated Press was used in this report.