The "Like" was for your honesty!

As others have remarked, I doubt that simply changing to a slightly heavier bullet by itself would have caused this failure though. Never-the-less, your error it would appear, and you owned up to it.

Did you break down the two surviving rounds and verify the powder charge found in them? It would be a good idea to do so.

An example, strictly with 2400, of how current and former published data compare. For years Hercules published 15.3 gr/2400/158 LSWC as a maximum load. At the same time many manuals were listing up to 16.0 grains! Current data is only 14.8. Since Hercules also showed pressure data I have always been prone to accept their data! What is the difference? The old Hercules figure was crusher derived or CUP, and the new is Absolute date from Piezo equipment. The funny thing is I have shot the same bullet/primer/gun with the 16.0 grains, and it is lower velocity than 15.3! Pressure, who knows.

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Gunsmithing since 1961