Lee collet die problem

[Footsore]

So I have a new Lee Deluxe Die set for 243 win and start neck sizing some unfired brass in the new collet neck die. All going well until on about the tenth case I hear a bang. The mandrel has pushed the aluminium top up and stripped the threads that hold it in the die body... I was applying some force as the instructions say at least 25lb but I am not a gorrilla and was really surprised. I know this cannot be normal and intend to take the die back for replacement but can anyone suggest what I might have been doing wrong?

[BillR]

Sorry, it was out of adjustment. Either that particular case was too long or just plain screwed down too tight. Check your instructions and you will see what I mean. It gives a warning about this in the instructions.

[boomtube]

"The mandrel has pushed the aluminium top up and stripped the threads that hold it in the die body... I was applying some force as the instructions say at least 25lb but I am not a gorrilla and was really surprised. "

It was too much lever pressure. And it was too much on the collet, not the mandrel. Lee's instructions are for Lee's presses, they can't tell each of us how much pressure to apply with other pressses. Case length won't have anything to do with blowing the top off. The leverage issue is how much upward force we put on the base of the collet anyway, not how much we push the lever. Lee's instructions say to adjust the die down until the lever is at right angle to the ram and then use about 20# of pressure but that obviously changes from one press to another. Once we form the necks to the mandrel there is no point to using more force, that can only push the cap out as your's did - it's designed to do that instead of busting the press or die body.

Starting by having the die UP until the lever is nearly full down before applying 20# of pressure increases the ram force tremendously; that's the point of a toggle lever system on a press.

[Footsore]

Thanks for the replies. I have a green unbranded O Frame press at least 30 yrs old that is similar to an RCBS and obviously now it is capable of applying to much force to these dies. Would I be better off buying a cheap Lee press for the neck sizing?

[7 loader]

This happened to me also. customer service replaced it for free. Do take the old threads out of the die.

[jsthntn247]

The instruction say to use a press that doesn't cam over when using the collet die. I leave mine in my challenger press for that reason.

[boomtube]

"Would I be better off buying a cheap Lee press for the neck sizing?"

No, use the press you have correctly. I do 'cam over' (that's a very bad misnomer) with all of my Lee collet neck sizers. But, like reloading itself, doing it correctly took some thought and experimentation.