I used FCDs for a wide variety of cartridges for many years. They work, but may not be necessary. I'd say my own efforts were inconclusive. Good loads that are built with care and attention to detail don't necessarily benefit from crimping. There may be a distinct benefit if all the parameters are not controlled.
There is also a write-up on how to find how much crimp. I think it starts with one 1/8 turn. It has been a few days since I've read it and there are parts of yesterday I don't remember. And access to loads that have worked for people with the Hunter and the Absolute.