[Blakenzy]

I have seen this printed on some primer boxes (S&B), so what is it exactly?

[Galil5.56]

It's a version of non-corrosive priming... Think along the lines of Kleanbore, Staynless, Sinoxid...

[caz223]

That sounds way too much like neurotoxin, and while multiple governmental agencies argue on your front lawn about how it's supposed to be spelled, they will find something wrong with you related to guns and you'll be branded a terrorist for life.
No thanks.