Firearms

.300 Blackout AR Pistol · Deep Dive

.300 Blackout AR Pistol

A longer barrel is a liability here — 200-grain subsonic clocked 1,139 fps from 16.5 inches, which is supersonic, the one thing it must not be.

The cartridge built so a short barrel would stop being a compromise, worked through from the numbers: velocity against barrel length measured rather than assumed, why supersonic and subsonic are really two cartridges sharing a case, the brace-and-SBR law tracked to the agency’s own filings, and the chambering mistake that destroys the rifle.

Photo: Three cartridges, .300 AAC Blackout by Silencertalk · CC BY-SA 3.0

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    Volumes

    1. Vol 1 Why .300 Blackout Exists — The Design Brief, and the Constraint That Shaped It
    2. Vol 2 Barrel Length Is the Whole Point — Velocity Against Length, Measured
    3. Vol 3 Supersonic and Subsonic — Twist, Gas, and Cycling Both
    4. Vol 4 The Legal Volume — Braces, SBRs, the Rulemakings, and Michigan
    5. Vol 5 Suppressor Host — The Cartridge That Exists Because Cans Do
    6. Vol 6 Building and Running One — Controls, Tuning, Optics, and the 5.56 Danger
    7. Vol 7 Owning One — Maintenance, Ammunition, and What It Is Actually For