AJC1
Member
This is kinda a loaded question because the platform may also have requirements. I roll crimp everything in 38 and 357 because I have lever guns. That is a platforming requirement. Certain powders have a better burn when a good crimp prevents early bullet movements the drives up inital pressure helping deflaguration. A lot of magnum pistol powders are in this category. A roll crimp is superior to prevent inward movement. A cannalure or crimp grove gives you a positive mechanical lock preventing shorter oal and rapid dissasembly. All crimps should work in conjunction with proper neck tension not in lieu of it. Their is another crimp running around that may pop up in discussions called a profile crimp. I have not used it so those with more experience and knowledge in that area can expound on it. It appears to be for magnum pistol cartridges as in never herd of it in rifle. The final crimp I know about is a collet crimp, Lee refers to it as a factory crimp. It seems well liked for ease of use but I've not seen and data comparing it to a roll crimp in rifle.
