Neck turning question

[Topwater]

I have virgin cases that I need to turn to accommodate my chamber. I have already expanded the necks with a mandrel. During that process, I felt varying levels of pressures needed to insert the mandrel. Question : would it be advisable to start over, size the necks with a smaller bushing, then use the expander once more before neck turning. I’m trying to insure that my turned backs as concentric as possible. Thanks.

 

[Bill Norris]

It may not hurt to go back thru them again but blowing out brass you might not see much gains. I would be more concerned with the next loads.

 

[rwj]

I’d run the neck expander thru the cases again to assess if the first pass improved their uniformity with respect to varying pressure. I suspect it has…

 

[Bc'z]

Were they tried and chamfered 1st before mandrel

 

[jepp2]

I have already expanded the necks with a mandrel. During that process, I felt varying levels of pressures needed to insert the mandrel.

What is the diameter difference between your expander mandrel and your turning mandrel? I expect it to be around 0.001" or slightly more. That clearance is probably going to be more significant than what you are likely to gain by reducing the diameter and expanding again.

 

[Dave M.]

Were they tried and chamfered 1st before mandrel

Most likely means SIZED and chamfered

 

[mikecr]

New cases come with varying neck IDs.
You run the expander mandrel through, that is matching your turning system, and turn.

You're not trying to match tension, but to setup for turn. That's all.

 

[Topwater]

Were they tried and chamfered 1st before mandrel

They were not.

 

[243winxb]

size the necks with a smaller bushing,

My bushing does not size to the shoulder, so I can not neck turn, using a fl type S bushing die.

I need to use a standard fl die that sizes the whole neck, to the shoulder.

 

[Richard Jones]

^^^^ or use a 1/2" collet with your choice of bushing. Collet goes to the headstock, caseholder in the tailstock, no power, just crank them in. It also works on a wood lathe...

 

[762plinker]

ya need to be more specific to get a decent answer.
is this a hunting gun, a fun target gun or a competition gun ?
what kind of brass, what caliber
i size all my brass, trim to length(else the shoulder cut will not be true)
deburr in and out,
then expand and turn,in two steps...final cut is under .001

 

[Bc'z]

Most likely means SIZED and chamfered

Freakin smat phones.
I meant to say Trimmed and chamfered.

They were not.

If not chamfered it would be my guess this is as to why your seeing the difference when you run the mandrel in

 

[mikecr]

There should be no need to downsize NEW necks before turning them.