[john kilgore]

SINCE CRIMPING ISN'T REALLY A SECRET, I'LL TELL !

Most any good reloading manual will tell you about crimping. Try the Speer as it was my first one 30ys ago, and I still reference back to it as some of the material was deleted from newer versions.
For revolvers... With most bullets with a crimp groove, you need to turn the case into the canalure with out crushing the ridges on the bottom of the groove (jacketed bullets). With heavy bullets and slow burning powders in magnum cartridges, use all the crimp you can with out deforming the bullet or "sizing" the case neck into the crimp die. (See Winchester and Hodgdons manuals for recommendation on Win-296 and H-110 -essentially the same powders except lot#'s and labels- both are manufactured by Primex-St. Marks powder facility in St. Marks, Fl).
For Semi Autos, a taper crimp that turns the case neck into the bullet without any more than a thin line where the edge of the case touches the bullet is proper. With SemiAutos, it is emperative that the case be sized sufficiently that the neck tension holds the bullet sufficiently to prevent set back of the bullet upon chambering.
See, no secrets at All. However, some crimp is necessary for max consistency of ignition/Accuracy, except in bolt action rifles.
The Speer manual has an excellent section on crimping/accuracy.