I managed to pick up some of those Hornady bullets in 200gr and 220gr in those older boxes here and there. Speer seems to be on the shelves over the past year. If you're not able to find bullets at your LGS or favorite online reloading store, contact Les Vollmer at
https://vollmer-bullets.myshopify.comas he makes several 375 cal bullets for the 375 Win in cast and jacketed versions that are very good bullets, plus you will love dealing with Les as he is one of the most professional and polite people you'll ever deal with.
Great selection of optional added goodies to offer the buyer you have pictured there!