New Cartridge: 458 dropbear
From TheFirearmBlog, by Richard Johnson - Inspired by the recent introduction of the 45 Raptor, an Australian shooter using the screen name of Quan-Time worked up another bigbore round based on the 308 Winchester case. The new round is called the 458 dropbear. Quan-Time details the cartridge and the process he used to develop it at the Overclockers Australia forum. If you have an interest in how one develops a new load, it is definitely worth the read. The initial load tested used a .458 caliber, 350 grain Woodleigh RN bullet over 42.5 grains of ADI 2208 powder. (Note: According to ADI, 2208 is approximately equivalent to Hodgdon Varget and IMR 4064. Read this for additional information.) This load produced about 1,600 fps without a crimp and an estimated chamber pressure of 24,500 psi – well under the maximum established for the 308 Winchester. With additional development, this cartridge should be well above 2,000 fps.
- See more at: http://www.thefirearmblog.com/blog/2014/06/04/new-cartridge-458-dropbear/#sthash.U7dP8oSU.dpuf