Originally Posted by ssmall
I have been struggling with neck sizing for factory/hybrid hunting rifles. It is my understanding that the process of neck sizing will ensure the reloader that the neck walls are CONCENTRIC.?
No, not really depends on the brass and the Neck die. Most neck dies squeeze the neck way down then drag an expander ball back through the die just like many FL dies. There is nothing "Concentric" about this process.
Then there are the "Bushing" dies, these dies squeeze the neck down to a desired size and do not need the expander button. This type of die can make very concentric necks, on the outside
of the case-not the inside. If the brass has any imperfections in neck thickness these imperfections will show up on the inside of the neck and in "Bullet Concentricity" or better known as "Bullet Run-Out". If you use a bushing die and want concentric necks(inside) thus concentric ammo then neck turning is the next step.
This brings us to the best Neck Die on the market today. It is of course the Lee Collet Die. This die is unique in that it squeezes the case neck around a Mandrel. Regardless of the imperfections in the case necks the inside of the neck is perfectly concentric and without any neck turning. You can most certainly have outside "neck runout" with the Collet die, but who cares, the bullet is on the inside of the neck and that's all that matters for nice straight concentric ammo. Get a Collet die and be on your way to solving your concentricity problems.