is it better

[Bruce_in_Oz]

The Lee "Factory Crimp" die is a "collet' type die. Probably better explained on their website, as per

Here: Factory Crimp Die - Lee Precision

Simple adjustment of the height of the die in the press determines the amount of "squeeze".

The actual "crimping" is done by a collet, not too dissimilar from work-holding collets commonly used on lathes etc. The trick is that the crimping force is applied radially and there is essentially NO axial displacement of the brass, thus not much chance of bulging the neck or buckling the shoulder.

The more "traditional 'roll" crimp offered on most other seating dies for rifle cartridges, requires that there be a cannelure groove, of consistent depth, in the bullet. The neck is essentially forced into the cannelure by the final secondary taper at the very top of the seating die "chamber". The trick is to back off the seating plunger AND the die itself and experiment until your bullets are seated (and crimped, if desired) to your satisfaction. It can get a bit fiddly.

I prefer to back off the seating die just enough so that the "roll-crimp" does not engage, then adjust the seating plunger down until the required OAL / depth is achieved.

The, if desired, it's time for the "Factory Crimp" die.