I have a number of .38s and .357s. I keep .38 loads in .38 brass and I keep .357 loads in .357 brass.

No matter how well I label stuff there would always be too much risk of a .357 load in .38 brass finding it's way into an older, weaker .38 revolver.

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Now...if I had just one .38 revolver and it happened to be a Ruger Police Service Six, a revolver designed for a steady diet of full power .357 Magnum loads, that was ordered by a police department in .38 Special, then I might consider using loads that produced .357 pressures in it.

That is after all what many of those departments actually did in order to get near .357 Magnum performance without the potential bad press of issuing .357s to their officers in the political climate of the day.