New Cartridge: 458 dropbear

    458 dropbear

    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 here.  If you have an interest in how one develops a new load, it is definitely worth the read.

    458 dropbear

    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.

    Thanks to Nik for the tip.

    Richard Johnson

    An advocate of gun proliferation zones, Richard is a long time shooter, former cop and internet entrepreneur. Among the many places he calls home is