Winchester 1885 SS rifles and other SS rifles were chambered in the 33 WCF cartridge. This also includes the 1886 Winchester
rifles, along with the 1895 Marlin.

Excellent brass may be reformed from annealed cases in 45-70 and 40-65 WCF. The 40-65 WCF cases are a bit easier to reform
into 33 WCF, even using just a 33 WCF sizing die. Annealing the neck and shoulder areas of 40-65 WCF brass tends to prolong the life of brass cases, both in the resizing step and the finished 33 WCF cases. Bullets for the 33 WCF may be obtained through Hawk, INC. and some discontinued Hornady FP 200 gr bullets may also be found, though discontinued for years now.

In single shot rifles, even 200-210-225 gr bullets designed for other 338 chamberings may also be utilized. One of the best bullets out there for hunting use is the Nosler 210 gr .338 Partition bullet.
Additionally, molds for .338 diameter cast bullets may still be found-as they have not  been discontinued.

If you want correct headstamp, I have New Jamison 33 WCF brass in my inventory.  Pricelist is in the sticky at the top of the classified forum.