When it comes to the Lee Factory Crimp die and cast bullets, some people swear by it and some people swear at it. If folks are prone to think Lee can do no wrong they fall into the former category and if they think Lee can pull a boo-boo from time to time they fall into the second category.
I don't own a Lee FCD, have never used a LFCD and don't intent to buy one just to find out who is right and who is wrong. I don't care about that enough to spend money for personal research into the subject.
I have loaded several hundred thousand rounds of 38 Special ammo and every round has had either a roll crimp or in some cases a taper crimp. It has worked for me for a very long time.