wolverine72

I just purchased a new lee collet neck die. I've never used these before, but have used other brands.

I resized some .243 win shells, and noticed that the neck was only being resized to .243" and the bullet was not seating firmly in the shell. I tore the die apart, and measured the mandrel. It was .240". This is the same diameter that my full length dieresizes brasstoo, and it firmly holds the bullet. So I don't think that the mandrel is the problem.

I am using a Rock Chucker Supreme press, and Winchester brass.

Am I not applying enough pressure? It sure seems like I am -- directionsstate that only25# is necessary. I can see where the collet is leaving rings in the outside of the brass. I am also running a nylon brush through the neck to remove excess powders, crud, etc before I resize. Am I perhaps doing something else wrong? I am turning the die one turns after makingthe dietouch the shell holder.Any ideas or suggestions would be appreciated. Thanks.

Pete D.

A couple of things to try. One - how old is your brass? The Lee collet die works best with new brass or brass that has been annealed. If your stuff has been fired a few times, the necks may be work hardened enough to cause the problem that you describe.
Two - try sizing a case and then rotating the case half a turn and sizing it again.
Pete

bigcountry

I would say you are not sizing hard enough. I do it three times. When I say that, I mean I size firmly, turn about 100 degree, size again firmly, turn my shell again and do it again. On some collet dies, I have had to remove the mandrel, and take a piece of emory cloth and put in a drill and reduce .002-.004. But I know folks who have overdid it.

As long as you bullet is being held without slipping in an out is all you care about.

steve4102

The Lee Collet Die is just about the best neck die ever invented. But, it is not uncommon for the Collet die to produce very limited neck tension. There is a very common fix and it can be handled two ways. One is to remove the mandrel from the die, chuck it into a dril and polish it down a few thousands with fine emery paper. The other is to call Lee and order a "Reduced" mandrel for you particular cartridge, they cost about $5.

Prairie Wolf

I have had that problem too, and I thought it was due to brass hardening. I was getting bullets that I could move with my fingers. The cases had been fired a few times.

I haven't experimented much with it yet, but I was thinking of using the collet die and then hitting the loaded rounds with the factory crimp die to increase uniformity.

wolverine72

Many thanks to everyone who answered my questions.

For my .243 Win die, simply turning it 100 degrees or so and crimping three times did the trick.

I just got a .270 Win collet die -- the three crimp treatment did not work. For that, I used some fine emery cloth (400 and 600 grit)and a drill, and took .002" off the mandrel. That with three crimps did the trick. Even with three crimps, it's nice to not use messy case lubricant.

Thanks again to all for your help.

Prairie Wolf

Another thing that I have heard about with collet dies. Sometimes the interior of the die body is rough. When the collet is pushed up, the roughness makes it require more force. Some took the dies apart and polished the inside of the die body.

I haven't done this myself, but have read about it.