.300 AAC BLACKOUT

Discussion in 'The Ammo & Reloading Forum' started by Infidel762, Sep 10, 2011.

  1. Infidel762

    Infidel762 New Member

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    Mar 20, 2011
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    Texas
    Anyone loading this round? Looking at building an AR chambered in this but can't find much load data on it.
  2. gdmoody

    gdmoody Moderator Supporting Member

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    Welcome to the forum, #762

    I personally can say that I have never heard of that round, but I did want to welcome you!!
  3. Infidel762

    Infidel762 New Member

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    Location:
    Texas
    Thanks for the welcome =)

    the .300 AAC BLK is a cut down .223 case that is necked up to accept a .308 cal bullet. I know it is either very similar or the same as the .300 WHISPER round from many years ago. Advanced Armament Company is using it with a 200gr bullet to run subsonic for their suppressors. I have learned a lot about it in the last week, however I have not seen much load data on it. A few are carrying the dies but I have not found powder and ballistic data on it. http://300aacblackout.com/
  4. JLA

    JLA Well-Known Member

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    new one on me too. Seems to me you could use .300 whisper data so long as you develop carefully from starting charge. The .300 whisper is based on the .221 fireball case, so all youd have to do is find out what the H20 capacity of the .300 whisper is and compare it to the .300 AAC, if they are pretty close Id feel comfortable testing a few starting charges for the .300 whisper with whatever weight bullet youre using in the .300 AAC case.. And just proceed from there. Loose primer pockets are usually the first sign of high pressures. you will go to reprime the brass and the primers will go in without any resistence. But also bear in mind that loose primer pockets are also a sign of worn out brass so make sure you do your load development in once fired cases. and dont reload any of them until youve finalized a safe load.
    Last edited: Sep 10, 2011
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