Neck turning

[Hammer101st]

Im forming 6.5-06AI brass from lapua 30-06 brass and once necked down the brass is going from 15thou neck thickness to allmost 18thou crazy thats to thick i read on the forum to turn the neck as a 30cal before necking down. Why do it before and not after

 

[Steve Blair]

Im forming 6.5-06AI brass from lapua 30-06 brass and once necked down the brass is going from 15thou neck thickness to allmost 18thou crazy thats to thick i read on the forum to turn the neck as a 30cal before necking down. Why do it before and not after

I do mine after any neck manipulation to account for any distortion the operation induced.

 

[Ringostar]

Some people might recommend turning first, to reduce donut forming. When necking down from 30 to 6.5, some of the neck will become shoulder.

 

[DocBII]

Hammer,

Makes it easier to size the brass and what Steve said. Helps to anneal before first turning and after completing the last sizing step and before a final neck turning @ 6.5 mm.

HTH,
DocBII

 

[jepp2]

Why do it before and not after

I done it both ways on necking down 30-06 to 25-06. I much prefer turning after I neck down. As mentioned by @Ringostar your neck shoulder junction will now be on the shoulder.

 

[Hammer101st]

I done it both ways on necking down 30-06 to 25-06. I much prefer turning after I neck down. As mentioned by @Ringostar your neck shoulder junction will now be on the shoulder.

Did turning the necks before help with the shoulder migration or didnt matter

 

[jepp2]

didnt matter

It is going to move. This is the batch I turned after necking down. One the ones I turned first, the location of where I lightly ended at the shoulder meant I had turned further down the neck than when I turned after.

 

[Hammer101st]

It is going to move. This is the batch I turned after necking down. One the ones I turned first, the location of where I lightly ended at the shoulder meant I had turned further down the neck than when I turned after.

View attachment 1364063

Mine is an AI so im guessing it still dont matter or do you think it would aid in the fireforming

 

[jepp2]

do you think it would aid in the fireforming

The neck is going to blow out no matter how thick. Fully blowing the shoulder forward is the challenge.

The hoop stress increases the pipe's diameter, whereas the longitudinal stress increases with the pipe's length. The hoop stress generated when a cylinder is under internal pressure is twice that of the longitudinal stress. Longitudinal joints of a pipe carry twice as much stress compared to circumferential joints.

Another benefit of turning after you neck down is that necking down introduces thickness variations into the neck. I try to minimize it by taking it down in steps. But you can always turn it some before you neck down and again after they are fully formed.

 

[mikecr]

I turn at native cal/thickness because in that original form it expands to fit the turning mandrel correctly.
Well, it has for most of my cartridges (except WSSM).
Then I neck up or down as desired.

It has been trial & error for me, with a few culled cases, to hit the right turned thickness so that the necks come in at my desired thickness after necking up/down.
I don't FL size necks, ever, and it seems like it could take more fiddling up & down to get mandrel fit than it would be worth.

I recently put a spreadsheet together to calculate & predict this, and hopefully remove trial & error.

Neck Thickness Estimate

When it comes to up/down cal changes, it seems pretty much trial & error to find resultant neck thickness. I turn NEW necks trial & error before up or downsizing to a different cal. This, because it is far easier to turn new/unsized necks. But it just dawned on me that this thickness problem...

forum.accurateshooter.com

 

[Hammer101st]

turn at native cal/thickness because in that original form it expands to fit the turning mandrel correctly.
Well, it has for most of my cartridges (except WSSM).
Then I neck up or down as desired.

Makes scence

 

[Hammer101st]

Since mine is a AI will it effect the crush location because of the little ridge turning leaves