"there is no instrument on the press that tells you how much pressure you are applying each time, it seems only reasonable that sometime you may apply 22 pounds and at other times 28 pounds. So that leads to the inevitable question: how does this inherent lack of precision using the Lee Collet Die affect accuracy?"
You are correct the pressure isn't calibrated and, no, the lever pressure, as such, isn't what matters for accuracy or anything else; all that matters is that we press case necks firmly against the mandrel. Once a neck is firmly squeezed against the central mandrel it won't get any smaller no matter how much we press the lever BUT we can easily push the top cap out of the die if we massively over do it!
With a Lee press and the lever pressure done by the instructions, the 25 # figure is probably correct but I wouldn't know because even tho I've been happily using Lee Collet Neck Dies for maybe 20 years I've never done it on a Lee press. So, how can you tell if you've pushed hard enough? Pay attention to the feel of what's happening and you'll be fine, trying to make it work 'precisely' by the numbers like a computer you won't! Understand that once the lever stops the ram won't move any further until something breaks.
I first run my ram/case fully up and screw the die down as far as I can get it to go, then release the lever pressure and screw it down another half turn or less and do it again. After each try I remove the case and see if a bullet will go in easily; if it still goes in easy I turn the die down a little more and try again, repeating that until I can't seat the bullet by hand. IF I can see four slightly raised "humps" equally spaced up the neck I know I've gone too far, so I back off half of the last change and lock the die body right there. That process will work with ANY press and the die won't be harmed either.
Last edited by wncchester; October 1, 2012 at 08:06 PM.