Lee Collet die

[shootsteady]

explain to me anyone who knows these dies well and had to alter them to make them deal with brass that doesn't size consistently with most in a batch.

I read a forum members explanation on a different forum who said place a washer over the case in the shell holder to keep the mandrel away for the inside of the case base to prevent the collet from not closing enough to size. I'm aware of work hardened brass and thick necks, that would prevent sizing, and annealing to aid spring back. I noticed the aluminum caps recess where the mandrel rises in, and need to remove a little more to keep it clear of the case base. I measured an RCBS shell holder and it's thicker sending the case farther in the die verses a Lee shell holder that's thinner to keep the mandrel away from the case head.

Update

I saw an idea that looks like it would solve the problem. Add a spacer under the lip located on the top of the mandrel. That will keep the mandrel away from the case head to prevent the collet from closing enough to size completely against the mandrel. I measured the thickness of the case head and there are variations, naturally.

 

[John S]

If the problem is the brass, you might try different brass.

 

[shootsteady]

If the problem is the brass, you might try different brass.

Nah.... I had a few here and there, last time just two, out of 40, but with the spacer it took care of it. Over the years I had trouble no matter what brass I used. I shouldn't post here until I figure things out, sorry. Lee's stuff isn't consistent, and a rep from the factory said that too. Like the oversized mandrels I got today had different thickness of caps on the top, (so it sit on top of the collet sleeve and doesn't fall through) , of the mandrels. I put a washer underneath it and spaced it to prevent contact on the inside of the case head of my brass that prevented the collet from closing enough to size. I told the rep, and he was.... huhmm a little thrown back.

Update

the recess under the aluminum cap needs to be deeper to allow the collet to size enough before mandrel binds against the case web and the aluminum cap