I usually crimp enough to get the case mouth diameter .001 or .002 under the max. diameter listed in my reloading data. One will have a lot of feeding problems when the case isn't crimped enough. However, you can do that without distorting the bullet.
Another trick is seat the bullet to the proper depth. Screw the crimp die down to where it just contacts the shoulder. Back the case out and turn the die body about 1/8 of a turn. Try that, push the case with the bullet end first against the end of your bench with just thumb pressure. See if the bullet moved inward. Keep on adding a little crimp until the bullet remains in place.
It does help to seat and crimp in different operations. Many folks use the Lee factory crimp die.