New brass versus once fired sizing question

[tpcollins]

I cleaned and tumbled about 60 rounds of once fired .204 brass yesterday and sized the necks today with my Lee collet die. I also picked up some new Remington brass the other day and ran them thru my die as well.

On the cleaned once fired brass I could definately feel the collet sizing the neck as it neared the end of the upstroke. The downstroke was very smooth. On the new brass I could feel the ball sizer drag considerably as it went into the neck and on the exit as well. This would make me think these two "batches" of brass are very different - yeah or nay? Thanks.

[flashhole]

I'm confused. The Lee Collet Neck Die does not have an expander ball that gets pulled up through the neck. It presses the neck down around a mandrel.

[mrawesome22]

Yep. No expander ball on the collet die.

[Tuzo]

Neck sizing and full length sizing are options for cases fired in bolt action and bolt/lever/semi actions respectively. Assuming that your once fired brass will be reused in the same rifle then the Lee neck sizing collet die is very good when used according to instructions. It is a different technique than standard neck sizing. I have had accuracy improvement with .223 using that die.

It is normally recommended that new brass be full length sized before loading and shooting no matter the type of action.

[tpcollins]

Whatever it's called - ball sizer, mandrel or whatever - there's more tension when it goes into new brass versus once fired brass. Is this an issue or not? Thanks.

[jepp2]

there's more tension when it goes into new brass versus once fired brass

Of course there is. You are actually expanding the neck on new brass.

With a full length die, the die undersizes the neck, then the expander increases the neck while still leaving it undersize from the bullet diameter to create neck tension on the bullet.

The collet die squeezes the neck inward and the mandrel limits the amount it is reduced. When finished, there is less neck tension in the brass than if it had been sized in a normal sizing die.

So when you are sizing new brass on the collet die, the mandrel is expanding the neck.

This is the reason brass will last longer while using a collet die. You don't overwork the brass in the neck.

[flashhole]

No, it's not an issue. The fired brass has the neck expanded from firing. The new brass comes sized down and ready to load. Yes, it will be a friction fit onto the mandrel because it is sized. No harm in what you are doing but unless the necks on the new brass are damaged there is no reason to run them through any die prior to loading.

[Major Dave (retired)]

it looks like there is a little bit of surface rust on the mandrel. If so, that will cause more friction. It can be removed quickly with 0000 steel wool.