Neck clearence?

How much is needed?

I went with Lapua 30-06 brass to form my 280AI rounds, during sizing the necks thickened.

Reamer print shows 0.3156 diameter at the neck so what should I turn the necks to?

Finished reloaded neck diameter should be .313" or less. That would give you a minimum of .0026" clearance.
Put a bullet in your reformed brass and measure the diameter. Neck turn accordingly, if necessary.

a couple of things to think about are . what your total clearance is take half of that number , this is the clearance per side of the case .

when cutting your brass if you cut .001" deep ,your case will be .002" smaller .

how good of tools you have to measure and cut with should be considered too . A high spot on the brass could take up your clearance if it's not noticed .

I'll say .002 total would be the absolute minimum on a bench gun .001 per side does not give much leeway for carbon or dirt or something like that . I'm going to say on a hunting rifle .004 would not be to much . that's .002 per side . this is one thing that when in doubt go on the loose side . this topic does get talked about fairly often on accurate shooter . here is a search list for you to look through .

http://forum.accurateshooter.com/search ... =relevance

I would also ask the gunsmith that did the barrel job .

I asked multiple places. For a hunting / field shooting rifle the consensus was 0.004-0.006 clearance. Fired brass from this gun measures 0.315 so I turned so the necks measure 0.3095 with a bullet loaded.