USRA Brake Rules

[LateModel B23]

Our track is going with USRA rules - but not sanctioning. Looking over the USRA rules I notice under the brake section it says:

12.6 Rotors must be steel and may not be lightened or drilled. Rotors may be re-drilled for different bolt patterns or larger studs.

Are the AFCO slotted rotors, such as part #6640104 legal?

[el paso mod 19]

I run USRA rules and I've been to believe that any "store bought" rotor was legal. They don't want some of us trying to lighten our rotors when we probably do not know the proper way to do so and not make the rotor dangerous. At least that is what I think.