Look at the study on AR about the effects of crimping with a Lee FCD. I use them on nearly all loads, even for my target rigs. Some folks crimp too much IMO, I use a light crimp.
Years ago I found it helped with SD and group size. Same thing that the AR test shows.
Is it needed? No. Can it help? Yes.
Shoot for groups both with and w/o to see what your results are. I have seen it help and I have seen it offer no help. It will not hurt.
Before you even tinker with crimping, you need to be sure your dies and loading practices are producing concentric ammo.
Good Luck
loder
