1st vs. 2nd shot neck turning

[tbrice23]

The shoulders on my new win. 300wm brass is going to move forward .020" after fire forming. I turned my last batch when it was virgin and ended up with about .020 of the neck left unturned when fire formed.

The brass turns so much easier when new but I anneal. So what do you all do with belted brass?

 

[Deleted member 46119]

Did you expand the neck on the new brass before turning?

 

[tbrice23]

Yes

 

[Deleted member 46119]

Bummer.

I can't figure out how that happens.

I guess you will have to turn them again.

 

[Mikecr]

Why didn't you turn the entire neck on your new brass?

 

[tbrice23]

I turn all the way and into the shoulder.

 

[bill123]

Sorry for hijacking your thread but maybe the answer to my question will answer yours.

When you resize a case, the neck gets longer because brass from the shoulder is forced up into the neck. Since this brass is coming from an area that didn't get turned, why doesn't what the OP is describing happen to all cases?

 

[tbrice23]

That was kind of my question . If I turn after the first firing it will be obvious where the shoulder will be. Otherwise I'm turning virgin brass as if the shoulder is staying there.

Things are easier on non belted cases.

 

[tbrice23]

Bummer.

I can't figure out how that happens.

I guess you will have to turn them again.

He's probably right.
These have been PFLS 3 times bumped .002" each time and neck sized 3 other firings. But I figure if I'd do it after FF it could keep this effect to a minimum.

PP are still tight, there's a lot more loads left according to wall thickness. (Cut these today. Left is 4th right is 5th firing. )

I might just re turn.

 

[Mikecr]

You said the shoulders are moving forward 20thou on fire forming, which can be normal for belted factory. That would have moved shoulders into turned portion of necks. Either this happened or it didn't.

You make it sound (in contradiction) like shoulders moved backward, away from the portion you turned earlier, leaving ~20thou unturned at the necks.

So from turned necks ending, which way did fired shoulders move? Well, the answer is forward as shoulders cannot move backward out of fire forming.
So there is something you're not telling us.
Did you FL size the necks at issue?

 

[tbrice23]

You said the shoulders are moving forward 20thou on fire forming, which can be normal for belted factory. That would have moved shoulders into turned portion of necks. Either this happened or it didn't.

You make it sound (in contradiction) like shoulders moved backward, away from the portion you turned earlier, leaving ~20thou unturned at the necks.

So from turned necks ending, which way did fired shoulders move? Well, the answer is forward as shoulders cannot move backward out of fire forming.
So there is something you're not telling us.
Did you FL size the necks at issue?

It might just be that Mikecr. I you opinion should I re turn as a maintenance issue?