Lee Collet Die Weirdness

[TwoTone]

I had something strange happen with a Lee collet die yesterday:

I was sizing some 300 RUM cases and everything seemed fine until I got a case stuck in the die. Hmmm....strange.

I tried bumping the handle up and down a couple of times but it stayed stuck.

I finally pulled hard enough on the handle to haul the case out of the die and it dragged hard the whole way out. It stretched the case shoulder out and cracked the case in the shoulder area. The neck was super tight on the mandrel.

I kind of just shrugged it off and continued. Several normal cases and then it happened again. This time I separated the case, which broke at the juncture between the case body and the shoulder. The shoulder and neck stayed in the die.

I had to file the shoulder off the top of the mandrel to get the mandrel out of the collet and there was the case neck and shoulder stuck really tight on the mandrel. I had to tap the mandrel out through the neck with a hammer.

I've never seen this and I'm trying to figure out what caused this.
-Nothing odd inside the necks
-Mandrel is smooth and has not been altered
-I have processed many cases with this die and this is the first time this has happened.
-The only thing different is that these cases were just annealed. I still can't see how the case neck could grip the mandrel so tightly.

After I got things back together I finished doing the rest of the cases after lubing the necks with mica.

Has anybody seen this before or want to suggest an explanation?

 

[denydart]

I think I've had similar experiences but nothing that extreme. I traced (I think) the problem to the collet fingers not springing back out when the ram is lowered. When they don't expand they maintain pressure on the neck and therefore the mandrel and you end up drawing the brass over the mandrel with tons of force. Take the collet out, spread the fingers apart a bit with a screwdriver and lube the outside of the collet so they are more likely to pop out after the compression stage.

 

[TwoTone]

...I traced (I think) the problem to the collet fingers not springing back out when the ram is lowered. When they don't expand they maintain pressure on the neck and therefore the mandrel and you end up drawing the brass over the mandrel with tons of force.

Yeah, that was the first thing I thought of when the first one got stuck. I figured the collet was still clamped down onto the case neck. But I checked and the collet sleeve was free to move. I took the cap off the die and the collet sleeve was free to move independantly of the mandrel and case, which were stuck together. The collet was definitely realeased, same in the second situation too.

The collet is polished and lubed as well.

 

[denydart]

Wierd is right then. Maybe the newly annealed brass is to blame. I don't know how hard you're pushing down on the lever to size the necks but it kind of make sense that soft brass may be "swaged" with enough force to flow and seize onto the mandrel. The aluminum cap on the die would probably pop off before that could happen but I see how it could .
Just to clarify, with the case that separated, the case went up and stayed there after sizing but the shell holder and rim had enough play to confirm the collet wasn't stuck too? I'm trying to picture this in my head but shouldn't the neck and shoulder have held the collet "up" onto the mandrel in the compressed position if that's where the case failed?

 

[TwoTone]

....Just to clarify, with the case that separated, the case went up and stayed there after sizing but the shell holder and rim had enough play to confirm the collet wasn't stuck too? I'm trying to picture this in my head but shouldn't the neck and shoulder have held the collet "up" onto the mandrel in the compressed position if that's where the case failed?

You're right, the case neck being stuck on the mandrel held the shell holder up against the base of the collet. Once I unscrewed the top cap I could tell that the collet was free. Then of course I ripped the case in two trying to pull it out.

*Edit* Thinking about it some more I see what you mean, the stuck case should have held the collet tight into the tapered piece that closes it. This die leaves about .020 of the neck next to the shoulder unsized so I think that is why I had play that I could see. It would either be that or the case actually started back out of the die and then got stuck. It didn't feel like it moved at all on the way out but I can't be sure. To have it move and then get stuck would be even weirder. (is weirder a word?)*end Edit*

I don't think I'm pushing too hard on the handle....at least I've never had any trouble before and I have a couple of other collet dies in other calibers too. Maybe I just don't know my own strength, eh?

The freshly annealed brass is the only thing I can think of too but its still very surprising to me that it could stick so hard with two cases where the rest of them just slid out of the die normally.

 

[SUB MOA]

LEE Collet Dies

I lost over half of my 300 WM brass using a LEE collet die. I followed all the instructions, polished and cleaned it and had the same sort of problems. Another problem i had was being unable to chamber rounds that appeared to have resized properly. The shoulders were very slightly pushed back, expanding the taper at the shoulder junction. After guaging and pulling a bunch of loaded ammo, I threw it away and bought a Redding Neck Sizing Die.Perfect, won't go back.

 

[denydart]

Geez, a 50% loss rate is crazy. I can't say I've ever lost more than 1 case out of a batch/loading session and never two in a row with the Lee Collet Die.

I wonder if problems creep up on this design the larger the caliber? I use one in 22-250 and one in 243. If I had to guess, the 243 has given me more trouble over the years - maybe a 2/1 ratio versus the 22-250.