Hi, all,
I emailed and just received a reply from Bill Stine. He confirms 500 million, but thinks the number might be closer to 600 million by now..

To add to this discussion, let us not forget about all of the motors produced by other companies other than Estes - Quest, MPC, Aerotech, Cox, FSI, AVI, etc, etc, Not to mention all of the HPR motors produced.

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