Thread: Pressure Signs
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Old March 25, 2013, 07:23 PM   #22
SL1
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Join Date: November 8, 2007
Posts: 2,001
Unclenick,

From the pictures, I too am suspecting the cartridge cases are showing imprints of rough chamber walls. But, the pictures are not clear on that with the dirt on the cases. Another possibility is that the pictured roughness is really just powder residue from a LIGHT load. That is why I asked him to wipe off the cases and send us another picture.

The pictures also show a significant angle between the expanded part of the case and the smooth part of the case on the right. But, from the photo provided, it is hard for me to tell if that angle is due to an over-expanded case due to high pressure in a large chamber or the opposite, from a carbide sizer ring reducing the case diameter a lot near the head and a light load not expanding it very much. The shadowing makes it hard to resolve the perspective.

As for QuickLOAD pressure estimates, they are not so good for revolver rounds. Velocity and pressure are often over-predicted with measured case capacities as well as the default capacities in the program (as you already know). That is why I rely more on pressure-tested data in manuals for the revolver cartridges. But, with .357 Magnum, there is a substantial difference between old CUP data and more recent psi data. And, apparently the factory ammo is likewise not as powerful as it was a couple of decades ago (except "Buffalo Bore" and "Grizzly" ammo). So, even seeing how his guns perform with factory ammo will be somewhat ambiguous unless we know exactly what ammo.

SL1
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