I know there are 2 main neck sizes for reamers, .290 and .296. My question, is one size for Norma and the other for Winchester?
I have heard that the Winchester brass is actually better but would like more opinions on this matter.
yes the neck diameter is important but that is can easily be adjusted with a good neck turner.
The biggest problem between the Win and Norma brass is the case head diameter not the neck diameter. I believe the Norma brass runs a .001 or .002 larger. So if your reamer/chamber was cut based on Winchster brass dimensions the Norma brass won't fit into your chamber. I don't own a 6.5-284 but shoot with enough guys that do that this is a fairly well known "problem". I would hve to double check to maake sure that it's the Win brass that is bigger. Don't quote me, jsut be aware there is a difference. Don't know how the new Lapua 6.5-284 measures yet though. Also Hornady is making this brass to give you another option.