As a mill guy i can tell you i have destroyed a good number of lathe turned parts by simply performing my task in the wrong order of operation. Its pretty common to destroy a prototype because we are unable to predict how stress will rear its ugly head during a machining operation. Over time we see patterns and begin to head them off. I think barrel fluting is dangerous to do unless done by the manufacturer for the same reason. They understand their process and will flute a barrel at the right time. Doing fluting after the manufacturer has finished their work is taking a chance in my opinion.