I started using Lapua brass for my 6.5-284 Norma. Problem is that I can't get the case to come out concentric. They are perfect before loading but apon bullet seating they just "bend". Does Lapua harden their case necks? I read on another thread about Norma brass having thicker necks. Same problem perhaps? I have had no problems with my Hornady brass.

What do you mean by bending???
Is the tapered portion of the case just below the neck collapsing downwards and into the case when you seat the bullet?

Otto - Time to pause and break out the calipers and start measuring. I only use Lapua brass in 6.5-284. I have not had any problems with neck tension, however, I did turn the necks. You might find that the necks are a little thick and may need to be turned.

I use a Sinclair neck wall thickness gage for this. If you already have a Sinclair dial indicator and RCBS pilot stops, the gage runs about $25.

Bending is in reference to what was once a concentric case to now being non-concentric from the base of the neck forward. There is no buckling evident in the case. This bend is usually by .001" to .002" at the ogive of the bullet. I am not crimping the cases during seating. Incedentally, after firing the cases go back to being concentric.

Check to see that your shellholder isn't gummed up,in the recess that holds the cartridge rim..................