As has been posted- don't overthink it. I use a Lee Factory Crimp Die almost exclusively for hunting ammo. The Lee FCD is the one with the collet "fingers" visible from the top. The regular crimping shoulder on the inside of most seating dies can work for crimping, but are difficult to set correctly and have a tendency to decrease neck tension not increase it.
To properly use a Lee FCD. First, adjust your bullet seating die so the internal crimping shoulder barely touches the case mouth- then turn out an additional 1/2 turn so it won't touch the mouth of even a slightly long case. Set the lock ring on the seating die there. Seat bullet so the case mouth is up next to the FORWARD edge of the crimp groove or cannelure. (Note- you can use a Lee FCD even on a smooth sided bullet but you have to be gentle with the compression) Start the Lee FCD into the press. Run a loaded cart all the way up into the press. Turn the Lee FCD down until you feel contact. Lower the cart and turn the Lee FCD down an increment. Raise the cart up into the die again and watch the collet "fingers" compress around the case mouth. Repeat process of turning die down in tiny increments until the collet "fingers" completely close and touch each other. Set the die lock ring there. Any more compression of the collet die will unduly stress the die and press and won't gain any more crimp.
And to determine if you have enough crimp... simply load magazine full and shoot all but last round. Measure its length to see if any change. Do this two or three time for confidence in the test. Easy to do at the range during regular shooting session. Magazine rifles, both stacked and tube type, are prone to jamming rounds into case due to recoil thus shortening overall length. Double rifles and revolvers are prone to "pulling" bullets in the unshot barrel (or chambers) thus increasing overall length. Plus rough handling, by whatever circumstance, can change length usually by jamming bullets deeper into the case.
Pic shows relaxed collet fingers before crimp process begins.
