Those o-rings on Lee collet dies....

[coyoteking]

The cap on top of the Lee collet die has an o-ring, similar to the Lee lockrings. Should you tighten the cap down hard and bottom it out, or do you leave it slightly loose, like an 1/8 of a turn short of bottoming out, so that the mandrel self aligns as it enters the neck of the case?

Same question for the Lee lockrings- tighten them down hard or leave slightly loose so the die self aligns as the case is run into the die?

 

[salarguy]

Snug them up, but don't bottom them out.

 

[Burton Urnie]

Not sure if this is right, but I tightened mine down. The cap is aluminum, I have striped more than one, in the past when sizing if left not tight.
(Maybe I'm leaning on the press too hard??)
I should add I've never stripped one that was tight, only if it was forgotten to tighten the cap.

 

[Longwalker]

Speaking of stripping the threads on those aluminum Lee die caps, ( i've blown out the threads on more than one) anyone know where I can get a replacement or retrofit short of special order parts from the manufacturer? Prefer steel if possible.

 

[Lead hammer]

Tighten the aluminum top caps all the way hand tight. not crazy tight. If you are blowing the caps out you are pressing way too hard. Stick with factory aluminum ones.
I use a Rockchucker, and cam over. Just set it up light, where you feel no tension, screw in the die like 1/16" of a turn at a time to creep up to the right neck tension. Once you just feel tension in the cam over you are close. If you measure the neck ID vs the mandrel in the die you see when enough is enough. Often you will just see three little vertical lines in the outside of the neck. That is a good indicator that you have plenty pressure and can even back up the die a bit while checking your measurement. Your neck ID will always spring back slightly so will not measure the exact same as the mandrel. ( 2nd, 3rd firing etc. ) When I have mine set right, I can hold the sized brass in my hand, cover the primer pocket with my finger, and insert the mandrel into the case. The mandrel will actually hydraulic ( not the right term I know ) and want to bounce out, build air pressure within the case.