"NT" headstamp

NT is usually used to denote "non-tox" in the states. I don't personally know of a non-tox magnum primer, but I wouldn't doubt it. Probably a Sintox from RUAG. If that's true, there should be no difference in brass manufacture, just the primer.
 
Kevin Thomas posted this in another thread

Hey Guys,

No, that's Lapua brass, made in Lapua, Finland, to the normal Lapua specs. The NT is for Nammo Tactical, our 338LM production operation in Mesa, AZ, and is meant to differentiate our production stuff from that loaded in Finland. But yes, the brass is all from the same place, same machinery, and same material. Good stuff, and a real steal at these prices.

Kevin Thomas
Lapua USA