Sounds like WSP wants to see who has been purchasing AR lowers since 7/1/10, sift through that list and make their own assessment.
Everyone on the list has passed the checks.

I'm not sure if this is legal. At least it doesn't make sense because legit gun sales will detect the bad SN by default.
Then I go back to thinking that they want a list of buyers of single, stripped lowers and sniff around from there.

For those not familiar, an M16 or AR15's serial number is on a part called the "Lower Receiver".
You can acquire a lower either stripped (bare), built (with lower components) or as a complete weapon.