338 LM neck recomendation

[liseo]

My gunsmith is assembling one 338 LM rifle, but aint sure about a good/best neck diameter dimension for max accuracy and good brass life.

Will use Lapua brass and Berger/Sierra 300 grains bullets.

What neck dimensions are you guys are using for this caliber and why?

Thanks

 

[338 Mollett]

I have 7 years in fooling with various 338's I like 5 thou over your loaded round be it neck turned or not.