Those primers are made in Russia at a plant a ways east of Moscow. First imported to the USA and labeled by PMC, later Wolf, and now Tula. I've no idea why the marketing and ownership is so much like a drug addict's mind; mixed up and always changing.
Ne're the less, they've been popular with comptitive shooters since their entry into the USA markets. Be sure your firing pin's strength is up to snuff (factory specs to +15%)as well as the pin protrudes between .055 and .065 inch from the bolt face at its stop. Otherwise, they won't perform properly and consistantly.
I've used them and highly recommend them.
US Navy Distinguished Marksman Badge 153
Former USA Palma Team Member
NRA High Power Long Range High Master
NRA Smallbore Prone Master