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Posted:  6/6/2014 9:05 AM #41973
CTD Blogger

Joined: 7/14/2009
Posts: 10828
Last Post: 8/20/2014
Subject: 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.


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458 dropbear

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