200's
I inclined to believe (no proof) that the vast bulk of .40/180's are intended for the .40 S&W and thus designed to expand in the 800-900 fps range.
Drive those same slugs to good 10mm velocities, 1200 fps or so, and I;m not surprised they get fragged.
I'm thinking though that .40/200's are likely intended solely for the 10mm. If that's true, they should hold together better.
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