Annealing and concentricity control methods

[jelrod1]

New to the site and have a few questions. I am currently two stage bushing sizing .308 Lapua brass to get the concentricity to my acceptable levels of around .001 or better. I use a redding bushing neck sizer first with a .339 bushing, then use a redding FL SB bushing sizer with .336 bushing to bring the neck in and set the shoulder back .001-.002. I mark the cases for indexing purposes between ops. Doing this gets me an average of .001 run out. If I skip running the larger bushing my readings are usually .002 or better instead of .001. What methods or procedures do you guys use to control concentricity? Am I over thinking this or missing something to make it easier?

Also, has anyone studied or have any measurements related to annealing and concentricity? This is something I have not done yet and wonder the effects of measuring over the brass's life.

 

[jonbearman]

The annealing will allow longer usage life of the case and also make neck tension more consistent.Another trick is to use the lee collet die and have the mandrel made custom to get your neck tesion the same every time.

 

[jelrod1]

Thanks. I've never thought about using a collet die. I do run a K&M mandrel through new brass to set the tension though. I didn't know if uneven hardening had any effects when sizing that could cause concentricity issues or not. Are you using that collet die on fire formed brass as neck sizing only or are you FL sizing then using it? I prefer to FL and set the shoulder back .001-.002 for consistency. Does make me curious to other people's methods.

 

[BoydAllen]

If you want FL sizing, use the collet die to size the neck, and then use a body die to do the rest. The order matters, I tried it both ways.

 

[kelbro]

Anneal and then this...

If you want FL sizing, use the collet die to size the neck, and then use a body die to do the rest. The order matters, I tried it both ways.

and you will have very consistent neck tension and very concentric brass.

 

[jonbearman]

Boyd is right on the money and you can take that to the bank.I look up to Boyd as he and others have taught me so much and he is wealth of knowledge.

 

[BoydAllen]

Thanks guys. But you need to go a little easier or I will get such a swelled head that none of my hats will fit, and I'll die of neck failure.

 

[jelrod1]

Thanks guys. I've never used this collet die you speak of. Looks like I need to pick one up and try it. I've always used the Redding bushing sizers, neck and FL. Is there no love for them around here or do you just get better concentricity with the collet?

 

[BoydAllen]

I have seen more than one case where someone needed a little help with a collet die, and some of them need a little minor detailing, but they are worth the little bit of trouble.They are a unique design, only made by Lee. Just remember not to operate the die without a case in the shell holder.

 

[thefitter]

... The order matters, I tried it both ways.

Do you have a theory why the order matters?

 

[BoydAllen]

Just a guess, but possibly less clearance around the body of the case in the collet die, giving better alignment? Something else that you might find interesting is how little the concentricity of cases is affected by body sizing. Do your own tests, and go with the results that you get. I was just reporting what I got.