Two years ago at the AT&T National, Titleist gave its staff players their first real look at some of its 712 Series of irons. Last year at the AT&T National, Titleist gave its staff players their first real look at the 913 drivers and fairway clubs.
And earlier this week at the AT&T National, Titleist showed its staff players the forthcoming 714 collection of irons, as a couple dozen sets were shipped to Congressional for some early testing.
Bringing the prototypes for the Titleist CB, MB, AP1 and AP2 irons that will make up the 714 Series is a big part of the development process. “All Titleist golf clubs go through this critical step to validate their performance before being launched to market,” the company says. 
Of the four models, the CB and MB underwent the least change. In fact, Vice President of Golf Club Marketing Chris McGinley told PGATour.com  that "the one thing we kept hearing from tour players was, 'Don't screw them up. '"
So Titleist didn't – instead, the club designers chose to keep the makeover minor, focusing mostly on touch-ups to the sole and overall shape of these classic forged blades.
By contrast, the AP1 and AP2 irons received more of a renovation to enhance their forgiveness, starting with making their heads more progressive down through the set to keep the feel more consistent from club to club. Also, Titleist added more camber to the soles and cleaned up the way the hosel blends into the clubhead.
"We made some significant changes to [the AP] irons," McGinley told PGATour.com. "How significant? I'd say this was the largest amount of change we've made since the franchise began."
The new clubs won't be formally introduced until the fall at the earliest, and the final versions will make up Titleist's 2014 iron offerings.