Dustin: could you please explain the pressure spike 9" from the muzzle?

Turn-of-the-century powder pressure-distance curves

[Linked Image from photos.smugmug.com]

c. 1930 powders and loads

[Linked Image from photos.smugmug.com]

Modern powders

[Linked Image from photos.smugmug.com]

I believe gun sellers report MWT at 9" from the muzzle because that is typically where the barrels are thinnest ie. about 20" from the breech and before the start of choke constriction. And IMHO that is not an adequate assessment.

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