Loading the .450 Bushmaster

A per-caliber loading dive for a cartridge that looks like a pistol case and loads like a rifle one. Why no carbide sizing die exists and never will, what that costs at the bench, seating against a magazine that has already taken the usual accuracy lever away, and how to work honestly from load data that only three publishers print.

Firearms

Loading the .450 Bushmaster · Deep Dive

Loading the .450 Bushmaster

It carries about .020 inch of taper, and a carbide ring is a straight cylinder — so every case gets lubricated, every time.

A per-caliber loading dive for a cartridge that looks like a pistol case and loads like a rifle one. Why no carbide sizing die exists and never will, what that costs at the bench, seating against a magazine that has already taken the usual accuracy lever away, and how to work honestly from load data that only three publishers print.

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    Volumes

    1. Vol 1 What This Dive Is For — and What Three Other Dives Already Answer The map, the component decision that gets made before anything else, and where the rest of the material actually lives
    2. Vol 2 A Straight-Wall Shape and a Rifle Process Twenty thousandths of taper, why no carbide sizer exists, and every consequence that follows from it
    3. Vol 3 Sizing, Lube, and the Stuck Case What follows mechanically from a case that no carbide die can size, and why this chambering punishes a skipped step harder than anything else on a mixed bench
    4. Vol 4 Seating and Crimp Against a Single-Stack Magazine The magazine is the binding constraint, the usual accuracy lever is unavailable, and the crimp everyone recommends is right for a reason nobody states correctly
    5. Vol 5 Thin Data — Loading a Cartridge Three Publishers Cover What it costs to work without a second table to check against, one pressure figure that is easy to describe wrongly, and the barrel-length error that sparse data makes dangerous