Sizing new brass

Depends how you will load in future.

I prep necks with a Lee collet die for most calibres I load & they end up with different (probably less) neck tension than standard sizing dies. Because of that, I open out necks on virgin brass with slightly oversize expanders I have had made, then size the necks down again with the Lee die.

I do chamfer my necks & some virgin brass I've seen (not the stuff I use) has some pretty out of round necks. I guess if you were going to chamfer them before your first loading, you might need to uniform the necks in some way first.

Finally, I guess it depends on how much you trust the manufacturer to produce a uniform product that will allow you to load for the best result in your rifles. If you can eyeball or measure irregularities, then maybe your peace of mind will force you to smooth them out.

John
 
I test a few cases by running through my sizing die - I had a lot of brass a few years ago that needed sized to chamber in my minimum spec chamber. If the random draw cases are not worked by the die, I stop that task.

I do expand every neck so that I can control neck tension, uniform the primer pockets, de bur the inside of the primer holes and chamfer the inside and outside of the necks.

JeffVN
 
I don't size it if it's new. it will fireform when I shoot it then I'll size and trim it when it starts to get a little hard to extract. If you are going to spray and pray from an AR, it's recommended that you size it everytime you load it..
 
New brass out of the box has soft (annealed) necks and the cases aren't lovingly placed in the container one at a time. Necks are frequently slightly dinged or bent and need to be rounded up and sized to give proper neck tension. The necks usually also need to be chamfered inside and out which is hard to do if the necks aren't rounded up with a die.

I always run new brass into a neck sizing die before using it, and trim them to length.
 
New brass out of the box has soft (annealed) necks and the cases aren't lovingly placed in the container one at a time. Necks are frequently slightly dinged or bent and need to be rounded up and sized to give proper neck tension. The necks usually also need to be chamfered inside and out which is hard to do if the necks aren't rounded up with a die.

I always run new brass into a neck sizing die before using it, and trim them to length.

Ditto.
 
Iron out the necks of virgin brass as well as deburr the inside of flash hole and chamfer in/ouside case mouth
 
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