Head stamp Z on 338 Lapua Brass?

[Hoppsing55]

Recently purchased some 338 Lapua Brass from Graf and Sons. This was advertised as being produced by a Major US manufacturer. Looks great, I expect it will work fine. Price was very good. But, I have never seen a head stamp Z? Anyone know what Mfg Co this is?

 

[Dmagna]

Probably unmarked military brass. Used to hide the origins of the brass. The US military along with others ordered brass like this, RUAG might have made the brass