There is a big difference between "disclaimers" and "valid safety concerns". It would be nice to write off everything you don't want to believe for the sake of an argument on a forum by calling them "old wives tales", but it doesn't work that way. Most reloading manuals do not go into internal ballistics because it is more than most handloaders care to hear, and adds a lot onto the cost of publishing a simple loading manual.

I'm not going to reread every book I've ever read because of this discussion, so I looked at the ones that had an index in the back of the book. They are older books and I'm sure those that want to disagree will dismiss them on that point, but I don't really care.

Naramore and Sharpe both stated that flash holes are determined by the factories based on the primers that the cases were intended to use and should not be enlarged. Sharpe noted that he had a ballistics lab do a test using .270 Winchester brass, comparing the factory size of .08" to enlarged samples with .101" flash holes. The average velocity increased 69 fps, and the average pressure increased 9000 pounds. This was using Hi-Vel #2 powder and non-corrosive primers. This is similar to what other books have said about larger flash holes, and the outcome of huge pressure increases with little velocity increases happens with a lot of the old wives tales too.

I'm not trying to change anyones mind about what they think, just saying to be careful where you get your info from, wether it be a gun store or the internet.