Hey guys and gals, I usually just stay in the 15-22 forums, but it is time to broaden my horizons and no I am not going to ask about reloading a rimfire

Anyway, as much as I shoot, I want to learn to reload and have been doing alot of research on it and a friend of mine does reloading also. As we know safety first !!! But I have just always wanted to learn how to reload..

But my friend has pointed me in the direction of lee 4 hole turret press and a hornaday 8th edition book, but my question regards .357 magnum loads, and he does not have a .357 to answer my specific question

It is my moms Colt Python that I want to start loading for, as well as my 9mm, SKS and others...I want to load hers for the 125gr. mark.

But I see Lee makes this 3 carbide die setup
3 die setup and they make this 4 die carbide set

I know the difference is that the 4th die is a crimper. Every .357 mag round I have shot i have never seen them crimped. So is it needed to crimp this round?

Thank you for the info and sorry if this has been asked before and the long rambling long post.

Jeremy