No more than necessary to remove all signs of any belling and to lay the case mouth flat against the bullet. Don’t try to make a case hold a bullet more tightly by applying a heavier taper crimp. If you are using a single stage press, you will need to set your die by measuring the dimensions of the finished round’s mouth. Measure the case mouth wall thickness with your calipers. Double the wall thickness and add the bullet’s diameter. Then subtract .001. This should give you a good starting point. On a progressive press, perhaps the best way to
go about setting the taper crimp is to use a case to set your die. Run a case into your resizing die. Moving the case to the crimp station, run the press up to the top of its stroke. Screw the die down until you feel it contact the case mouth, and turn it 1/8 to 1/4 turn deeper. When a cartridge is loaded, this should give it about the right degree of crimp.
