First of all, a "ghost gun" is no more of a threat than a gun that started out in the traditional supply chain and ended up in malevolent hands. The serial number, the paperwork, all that stuff does nothing to prevent the crime -- it only serves to facilitate apprehension of the criminal after the fact. Spree killers don't give a crap about any of that; they intend to end up dead or in custody anyway.

Secondly, what makes you think that the suppliers of all the various bits and bobs that are required in order to turn a "ghost" receiver into a functioning firearm are not NRA-supporting members of the gun industry?

Finally, please show us where in the NRA has advocated for the killing of school children. Verbatim citations only, please.