Some load combo's will preform better with a -.002 and once in a great while a -.003 Bushing...I try both for grins and giggles.
I have noticed that when the bolt closes easy on one round, tad more difficult on another round, then hard on another round that flyers abound in the group.
The use of neck bumping dies eliminates this issue without having to go to the trouble of full length sizing.
Forester standard neck sizing dies will bump shoulders and you can send the die back to the factory and have the neck honed to a specific size for $12.
Certain cases I shoot run high pressures at the top end accuracy node, and for hunting, I never want a hard closing bolt.
Two issues we reloaders face that can plague our reloads due to various Rockwell hardness in brass, dia. at the web of the case, and length of the case. Unfortunately, production dies of all brands are subject to SAAMI spec and the dimensions of a factory chamber are helter skelter. Often, you have to push the shoulder back .006 or more to reduce the size of the web to where the bolt feels easy to close on some brass. This causes short brass life when you have to push the shoulder back more than .002. Often, it is more cost effective to go ahead and over work the brass vs spending the money on custom dies or separate the sizing process into two different sizing operations.
Part of the accuracy equation is alignment, which is getting the bullet started into the barrel straight. Having the brass lay in the chamber with as much precision as you can possibly get is a huge step in getting the bullet started straight in the barrel.
