450/400 Nitro Express brass.Hornady is now producing new unprimed brass for 450/400 3” Nitro Express and 450/400 3 ¼” Nitro Express. 450/400 3” is also known as 400 Jeffery and is the only chambering of the 450/400 still in production. The original 450/400 3 ¼” chambering was a black powder cartridge, when smokeless loads where developed for it the higher pressure caused extraction problems. That version had a very long straight neck. Jeffery modified it moving the shoulder further out and shortening the case by ¼”. This increased the case capacity and eliminated the stuck case extraction problem. They named their version the 400 Jeffery but other gun makers not wanting to advertise Jeffery’s name just continued to call it a 450/400 Nitro Express but added the 3” distinction. Although gun makers still made both versions for several year, eventually all production of new guns ended until Hornady and Ruger resurrected the chambering in a Ruger Number 1 with several other double manufacturers like Sabatti following suit. When buying your brass for reloading, please be sure of the version you have as they are not interchangeable.