Lapua Spring Back

[Twud]

I just starting to work with a box of new Lapua 6BR brass for a rifle I have on order. The gun is being chambered with a .265 neck and the Lapua brass has a .268 neck. I have a Sinclair neck turner and the cases won't fit over the turning mandrel. I am not real impressed with the run out on these new cases anyway so I decided to run them over a Sinclair expanding mandrel. The cases go into the mandrel at .268 and come out of the mandrel at .268, and still won't go over the turning mandrel. The expanding mandrel is .242. Could there be that much spring back in the Lapua Brass?
When the mouth first meets the mandrel there is a bit of resistance, maybe the first 1/3rd of the neck, and then goes the rest of the way by the weight of the press handle.
What am I doing wrong? It's as if the necks don't have the same inside diameter from top to bottom.
I know I'm missing something I just dont know what it is
Mark

 

[anyrange]

Are you sure that you have an expander mandrel and a turning mandrel, and in the right place. For years I had two turning mandrels and turned necks on a very tight mendrel.

 

[billmo]

Don't sound like the expander is sized right. Measure both with calipers and see what you come up with. Som'um ain't right about that. Bill

 

[DaveBrokos]

Have you checked your new brass. I ran into a batch of Lapua brass that would not size properly. Not all but about 30 percent of the brass inside diameter was bad. Had to throw away about 30 pieces of brass. If not sinclair will replace your Expander. Your turning mandrel should have A24 on it and your expander should have E24 on it Hope this helps