Firearms

The AR-15 in 5.56 · Deep Dive

The AR-15 in 5.56

The pressure figures everyone compares are not measurements of the same thing — SAAMI reads half an inch behind the case mouth, NATO reads at it.

Stoner’s rifle and the service lineage behind it, then the parts that matter: what mil-spec actually guarantees on a lower, how barrel length trades against gas length and dwell, why twist is set by bullet length rather than weight, and the 5.56-versus-.223 question answered from the chamber prints instead of the folklore.

Photo: Edgar's first AR-15 by Mitch Barrie · CC BY-SA 2.0

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    Volumes

    1. Vol 1 What the AR-15 Actually Is — Stoner's Rifle and the Service Lineage
    2. Vol 2 The Lower Receiver — The Part That Is the Firearm, and What Mil-Spec Guarantees
    3. Vol 3 The Upper, the Barrel and the Gas System — Length, Dwell, Twist and Steel
    4. Vol 4 5.56 NATO Versus .223 Remington — The Chamber, Not the Powder
    5. Vol 5 Building One From Parts — Carriers, Triggers, Gas Blocks and the Order of Assembly
    6. Vol 6 Optics, Furniture and Accessories — What Suits a 16-Inch Carbine
    7. Vol 7 Owning One — Maintenance, Wear, Ammunition, Magazines and the Michigan Position