An excellent all-copper are the Knight Bloodline bullets, which I hear surrender the biggest blood trails.
Its pretty obvious the Bloodlines are made from UNSC3600 brass.
http://www.knightrifles.com/product-category/muzzleloader-bullets/bloodline-muzzleloader-bullets/http://www.lehighbullets.com/products.asp?cat=31Material - UNSC36000 brass