Forster oversize expander ball size for 6BR lapua brass?

[Oldschool1]

Can anyone tell me which expander ball may provide "hand bullet seating neck tension", or rather allow the bullet to be seated into the lands such that when chambering the bullet will bush back into the neck rather than jam the lands.

I'll be using this 1st time to expand the new brass necks after running through a Forster shoulder bump die (really neck conditioning only the first time through). Most likely I will use a .268 bushing with Lapua new brass.

So I imagine "spring back" is also a function of the neck ID dimension after necking down in the bushing, and prior to the expander ball - hence a 0.268" bushing for starters, next down I have is a .266" bushing.

I'd like to go light on neck tension and low deformation. I may not need to use the expander ball afterwards, but thought i'd shoot for low neck tension -low working first time through.

I suppose I could just expand the neck, simulate fired case, then neck down with the bushing.

First guess at expander ball is a .2435" that may leave .0005 tension when using .268" bushing?

Any thoughts appreciated.

Thx,

Paul

 

[dkhunt14]

I don't know what distance you are shooting, but in my testing with a Dasher, the more tension gave better groups and less vertical at 1000 yards. It just seemed to even things out. I have seen guys use the no or low tension and they always seemed to get wild fliers. I have used as much as .006 sizing to give more tension. Now this was at 1000 yard BR. If you want little tension, I would imagine something in the .2425 to .2435 would give what you need. It would be determined by brass thickness and springback. I never use a button on a die but expand with an expander die and mandrel. Matt