Expanding necks

[grovey]

Is there a proper way(s) to expand the neck of a case without losing length? I'm tinkering with the idea of a 30 T/C rifle build, and would be using 6.5cm brass for the rifle. When I ran a few old 6.5 cases thru a 30 T/C fl sizing die it shortened the o.a.l by .020. Although expanded, the datum measurement stayed the same as before expanding using the same hornady headspace insert. The cases were annealed beforehand, and I used a generous amount of imperial lube in the necks. I would think this is akin to expanding 6br to 30br since the cases are also very close?

 

[Whisky Tahoe Foxtrot]

Expander Mandrels can be used to open the neck. They tend to have a taper which makes them easier to use than pin gauges, though if your taper your pin gauges they work great as well.

 

[skeeljc]

The material has to come from somewhere.

 

[457ciSBC]

Is there a proper way(s) to expand the neck of a case without losing length? I'm tinkering with the idea of a 30 T/C rifle build, and would be using 6.5cm brass for the rifle. When I ran a few old 6.5 cases thru a 30 T/C fl sizing die it shortened the o.a.l by .020. Although expanded, the datum measurement stayed the same as before expanding using the same hornady headspace insert. The cases were annealed beforehand, and I used a generous amount of imperial lube in the necks. I would think this is akin to expanding 6br to 30br since the cases are also very close?

However, you have changed the location of the neck shoulder junction and the displacement isn’t free.

 

[Bill Norris]

When moving that much the cases will get shorter as you supposed.

 

[KMart]

SAAMI reamer prints show that the 30 T/C has a shoulder that is .022 longer than the 6.5 CM. That prevents the loading of a 30 cal bullet in a 6.5 rifle.
When you fireform your 6.5 cases in the 30 T/C, you will get your .020 back
6.5 30 T/C
OAL 1.9250 1.9300
Base to shoulder 1.486 1.5076

 

[grovey]

Sounds like the way I did it I may end up with too much headspace to fireform unless I'm jamming bullets. That, or an oversized mandrel, and then a false shoulder with my fl die to shoot cow to fireform?

 

[Willie]

I've got better results using a false shoulder over jamming the bullet, but no experience with 30 T/C, just 6.5 & .284 wildcats.