I'm a plinker loading A#5 6.1 grains Eggleston 115 cnbb (0.357) and 7625 4.2 grains Darda's 124 non-shouldered lrn (0.357) in range brass. Using not enough crimp, the bullets walk/creep and some have even exited the casing while in the cylinder. With max crimp I get bullet tumble/keyholing and even a slight bit of walking (several thousandths of an inch, but usually less than 10). My starting COL is around 1.100. I use the Lee carbide dies, including the FCD, but have replaced the decapper/sizing die with a EGW undersize die (which is made by Lee for EGW).
My thoughts at this point of frustration: Back off on the max crimp to alleviate tumble, lessen the COL a bit to compensate for walking and just "put up" with some bullet creep and call it a day. But I'm open to suggestions on how to get this right.