"In our plant we have an experimental Magnum that has been fired, in the course of the past three years, well over 9,000 rounds of the S&W .357 Magnum ammunition, and very nearly double that number of other cartridges in the .38 S&W Special group. In order to determine the effect on the arm when using the shorter Special shells in the long Magnum chambering we did not clean the barrel or chambers of this revolver during this period, and we are very glad to say that recent tests showed that the accuracy of the arm had been affected in no way, nor were there the slightest signs of ill effect in any way whatsoever."

This is an interesting paragraph. I think these were hotter rounds of 357 Magnum than we use today but they didn't have any problems with extracting Magnum brass after firing many rounds of 38 Special from the chambers and without cleaning them.