Neck turning case prep

[Hengehold]

One of the technical articles on the accurate shooter main page discusses neck turning. I have included the link below for reference. It specifically recommends that a NON-BUSHING FL sizing die is used to size the brass immediately prior to neck turning. I understand that a bushing does not go all the way down to the shoulder. My question is, what exactly is wrong with using a bushing die?

The neck turning tool from K&M will turn the neck while the pilot cuts the doughnut out of the inside of the case. So why do I care if the neck is sized all the way to the shoulder? I can cut the doughnut from the inside and the excess material from the outside at the same time. Seems like this negates the need for worrying about if the doughnut is pushed to the inside of the neck or not. What am I missing?

Thanks,
-TH

 

[PopCharlie]

I believe it's a good idea to get the necks as straight as possible before turning. In my experience, runout on the neck will cause inconsistent neck wall thickness after turning. Non bushing full length sizing dies, like Forster BR dies, make straighter necks than bushing dies.

PopCharlie

 

[Bc'z]

Think about this...
If the mandrel and cutter are fixed objects, and neck essentially has a tapper to it, when cutting the out side of the neck you are cutting the unsized portion thinner than the rest of the neck that was sized.

 

[butchlambert]

This is why I fireform without a bullet prior to neck turning.

 

[Bc'z]

This is why I fireform without a bullet prior to neck turning.

Do you go to a larger turning mandrel to accommodate the fired brass inside diameter?
I've got some Peterson id like to turn, and don't have a FL die for that cartridge.

 

[butchlambert]

Do you go to a larger turning mandrel to accommodate the fired brass inside diameter?
I've got some Peterson id like to turn, and don't have a FL die for that cartridge.

I only trim to length before fireforming. No need to size them first. Remember that I'm fireforming an unturned piece of brass. It will need to be expanded very very little before turning. After turning neck size only. Why work your brass unnecessarily?

 

[marchx]

Using a standard cutting pilot from KM on 6.5 creedmoor brass I cannot turn sized brass after expanding the neck with a mandrel. The pilot diameter is too large. It fits only fireformed, unsized brass. Is it ok?

 

[piie]

I believe the idea is that you want to push any unevenness in the neck wall to the outside, where you will be cutting the high spots off. A bushing would push the unneven spots to the inside.

 

[butchlambert]

I have found that all mandrels and pilots aren't matched. Use a K&M expander with your K&M neck turner. I have mandrels for my K&M, Stiller, and Pumpkin turners.

 

[Bc'z]

I have found that all mandrels and pilots aren't matched. Use a K&M expander with your K&M neck turner. I have mandrels for my K&M, Stiller, and Pumpkin turners.

This is kind of the basis to my question.
If you're turning fire formed brass, wouldn't the inside neck diameter be a few thousandths larger than your turning mandrel, hence needing a turning mandrel of a larger diameter?
I know the turning mandrel is roughly .0005-.001 smaller than expander giving a good fit with clearance.
Or should I not worry about the extra clearance as the brass is riding the mandrel on top and held there by the cutter?
I'm using 21st century lathe setup.

 

[butchlambert]

No, you will have to expand very little as you are fireforming unturned brass in a neck turned chamber.

 

[Hengehold]

Think about this...
If the mandrel and cutter are fixed objects, and neck essentially has a tapper to it, when cutting the out side of the neck you are cutting the unsized portion thinner than the rest of the neck that was sized.

This is what inspired my OP. Seems like if there is NO doughnut present then a tapered neck would result in a tapered thickness to be cut with the case mouth being thicker than the base of the neck.

However, I am making cases that involve lengthening the neck so part of the shoulder becomes the neck and the doughnut forms (6XC). In this particular scenario I suppose that one can get away with this kind of error because the base of the neck is indeed thicker to begin with. Is this flawed logic?
-TH

 

[Bc'z]

This is what inspired my OP. Seems like if there is NO doughnut present then a tapered neck would result in a tapered thickness to be cut with the case mouth being thicker than the base of the neck.

However, I am making cases that involve lengthening the neck so part of the shoulder becomes the neck and the doughnut forms (6XC). In this particular scenario I suppose that one can get away with this kind of error because the base of the neck is indeed thicker to begin with. Is this flawed logic?
-TH

All I know is I want an even cut, as far as having to form brass I've never gone down that road.

 

[Willie]

The O.P. hasn't stated if he's using 308, 243 or other case to form the 6XC nor his chamber neck ID reflecting the turning.

I watched my mentor forming for 6XC years ago using 308 brass. At one time I saw @Lead Slinger describing the same easy method to form completely.

If he's still here, the OP should PM him or another 6XC shooter.

 

[jepp2]

@Lead Slinger

@Ledd Slinger

 

[RCE1]

Would you anneal prior to turning? I could imagine that inconsistent hardness would have an effect on the cut, especially if the cases were formed or necked up or down?

 

[Ledd Slinger]

@Ledd Slinger

What did I do? Am I in trouble? Lol!

 

[Willie]

@Ledd Slinger

LOL! They sound just alike!!!!!

 

[Willie]

What did I do? Am I in trouble? Lol!

Whoops! I used you to help the OP. You haven't got in trouble yet! We'll seen if you do.

 

[Ledd Slinger]

Don’t really want to get into the finer details of forming 6XC cases because I’m pretty sure I went into fairly good detail back when I posted a thread on my process years ago. When you form brass that much it’s never going to be as good or stress free as ready made brass. Annealing is required and neck tension is hard to keep consistent. And that’s why I abandoned the 6XC a long time ago and turned the rifle into a 6mm Creedmoor for which I use Lapua brass.

Norma makes brass for the 6XC but it’s junk if you want to push pressures. Peterson also offers ready made 6XC brass but I’ve had bad experiences with that company so I stick with Lapua or ADG.