I half-jokingly posted that I would part with my CC charging handle. Sure, I would sell it for $500 but I doubt anyone is willing to pay that for a charging handle (got the idea from Unobtanium's post).
I took a look at what Benelli offers in the way of charging handles for the M4 on the Benelli website. Three are listed, and it appears only the OEM style has the detents on the end of the shank, the other two are milled 360 degrees so therefore those will spin in place. I don't have a FFT charging handle to compare, but based on the photos of the FFT charging handle on their website it appears FFT has the same profile of the OEM detents on the shank of their charging handle. Perhaps someone who has a FFT charging handle can verify this.