Neck sizing new brass

Steve gavette

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Jun 22, 2019
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Glendale, AZ
Just got a batch of brass. I have always reloaded, never purchased new brass before. I checked the neck size, and it is already smaller than I wanted. Hadn't thought about it and wasn't expecting that. Do I need an expander to open up past the desired neck size and then run through the bushing die?
 
Neck sizing mandrel 2-3/1000's under bullet caliber is one way. This will "fix" any dented necks on bulk brass. The expander on your regular dies will likely do the same for you. Hard to be more specific not knowing your caliber, die manufacturer, style of dies and make of brass. Unfired brass is almost always undersized in the neck, shoulder and body before firing.
 
I lube the neck of new brass with Dry Imperial, using a Q-tip and run a
.002 under caliber mandrel. Seating bullets is more consistent with the Imperial in the neck of new brass, also.

I never use the expander ball anymore. I just take them out of the FL die, run fired cases thru and open up necks with the mandrel.

On my bushing dies, I use a bushing that will size neck ID down .003" or .004". Then I use a mandrel to open neck up, usually .0015 or .002" under caliber.
 
I have a neck only die for every cartridge I shoot. The neck portion is honed to my specs and the sizing button is also sized/polished to my specs.
This ensures that all my loads, whether new or fire formed all have the same neck tension.
I found more than 2 decades ago that new brass is way under what I strive for when I load once fired...so I fixed that.

Cheers.
 
The mandrel is very effective in controlling runout. The 21st Century mandrels are very well made and don't load up like some other brands. Many sized mandrels to choose from for tension tweaking. Their EL expander die body fits all but one of my cartridges. Good luck
 
I use mandrels too, but the Neck only dies I have are faster and only move the neck a total of .003" with spring back and I also run graphite through all of my necks.
Most FL/Neck dies, unless custom, move the neck .006"-.008" undersize, then the expander takes it up an additional .004"-.006". This is far too much working of the brass.

Cheers.
 
When you say the necks are too small, what more can you provide? OD, ID, thickness?
If you can seat the bullets, well you have to fire form anyway, and the necks should be fixed with that.
 
when I get new brass I always make sure the primer pocket , and flash holes are uniform. I will load all of them up with cheap bullets and a mid range load then shoot them. Next step will be to size them to fit my chamber. If your getting a accurate load with new brass then I will run the expander ball all of the way down on the die so I can uniform the inside of the case neck then load them up
 
I full-size my new brass and mandrel die, turn my necks, and then full size and mandrel again before first loading. Then I anneal with every loading after that
 
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