Misplaced it, but years ago, I called Hornady on one of their bullets, the SPSXs, that was giving just a puff like your breathe on a cold day, when it was 90 degrees outside.
they gave me the formula for figuring out the RPMs the bullets were turning out of the Muzzle.
said the SPSX was design for about 180,000 RPMs...
my load with a one in 7 twist rifle, they were turning like 320,000 RPMs...
disintegrating about 6 inches outside the muzzle.
