Do not. Have used annealing and mandrels to establish proper neck tension, and bullets without cannelure groove with consistent results/SD in 223/6.5GR/6.5CM.
I do not crimp the Grendel or any other AR15 or AR10 cartridge. I do own Lee FCD for several of these cartridges but have always seen better results without using them, regardless whether there is a cannelure or not in the bullet.
The only "sorta" exception is using a crimp die to remove case mouth flare when loading cast bullets. But even then no crimp is applied, just a straightening of the case mouth.