300BLK/300Whisper question

Discussion in 'AR-15 Discussion' started by sweeper22, Dec 28, 2013.

  1. sweeper22

    sweeper22 New Member

    I believe the answer to this question is a resounding "YES!"...but,

    I'm just finishing my first 300BLK build. Can I fire any '300 Whisper' round from this gun and expect identical results? BTW, this is supersonic ammo...ie: not suppressed...yet.

    I only ask because I'm finding some interesting deals on the Whisper at the moment...
  2. msup752

    msup752 New Member

    Whisper will fire in Blackout but not the other way around.
    There are tiny differences between the two and I have no experience with any performance issues using whisper in Blk.

  3. robocop10mm

    robocop10mm Lifetime Supporting Member Lifetime Supporter

    The Whisper is based on the .221 Fireball brass, necked up to .30 cal. The BLK is based on the .223, cut down and necked. The BLK has a much thicker neck. The chamber is made to allow for the thicker neck. You will get more neck expansion upon firing with the Whisper and possibly more gas blow by. This will affect performance to some degree. No you will not get "identical" performance with the two, but pretty close