Oh, and light loads in pistol cases cannot "detonate". Nor in rifle cases, either. Smokeless powder isn't shock-sensitive.
What DOES cause trouble is that light loads are prime candidates for double-charging, since they almost never fill the case enough to make a double charge obvious.
A sound .357 rifle won't be distressed by a double charge of that load I just posted, btw. Pressure calculates as within spec for a +P .357 load.
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