The crimp is of less importance than is the internal capacity of the cartridge case. Handgun cartridges are very sensitive to changes in case capacity. Seating a bullet deeper or more shallow will change chamber pressure and velocities drastically.
Often time "special" loads will not develop enough pressure to burn completely or uniformly when loaded to magnum internal capacities. It behooves us to duplicate the internal capacity of the case the load was developed in. At least to some approximation.
I too load using 44 special load data in a 44 mag case but I have been crimping cast bullets using bullet's crimp grove. Thus ignoring the OAL and consequently not coming close, apparently, to achieving the book data fps.
Is there data, a formula, or otherwise a rule of thumb that would apply to say add (fill the blank) .grains of powder to replicate special load chamber pressure and velocity when using mag brass?
