Thread: Whats your fire forming process?

Originally Posted by Willus

Looking at fire forming some cases. What is your process and components (powder, filler etc) you use?

Don't listen to those other fellas Willus, listen to the Moa.

Head spacing is the concern when fire-forming. If there is no formed shoulder to support the case it will be driven forward and then on ignition the case head will stretch back until it hits the bolt and bugger the case by thinning the brass or even split the case and separate the head. Probably stuff you have already been reading about. The very best way around this is to set your neck size die so that it does NOT fully size the neck but leaves a donut ring at the neck / shoulder junction. Adjust the die so that a case can be chambered but is firm on the bolt. The case is head spacing and held tightly in place between the neck ring and the case head. Load a normal standard load and go hunting

Originally Posted by Moa Hunter

Don't listen to those other fellas Willus, listen to the Moa.

Head spacing is the concern when fire-forming. If there is no formed shoulder to support the case it will be driven forward and then on ignition the case head will stretch back until it hits the bolt and bugger the case by thinning the brass or even split the case and separate the head. Probably stuff you have already been reading about. The very best way around this is to set your neck size die so that it does NOT fully size the neck but leaves a donut ring at the neck / shoulder junction. Adjust the die so that a case can be chambered but is firm on the bolt. The case is head spacing and held tightly in place between the neck ring and the case head. Load a normal standard load and go hunting

Same thing is achieved by seating a projectile so the base is firm against the bolt face. Common knowledge to most that run improved cases.
If forming without projectiles I run a larger button thru the neck so I get the same results.


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Originally Posted by R93

Same thing is achieved by seating a projectile so the base is firm against the bolt face. Common knowledge to most that run improved cases.
If forming without projectiles I run a larger button thru the neck so I get the same results.


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Agreed R 93, only thought is that if the projectile is tooo tight there could be pressure problems with a standard load. Also we don't know how far out Willus would need to seat to touch the lands, so keeping on the safe side what you suggest is probably fine for a more experienced reloader IMO

Context

I'm sizing 308 palma brass to 260

Aim

To get the cases reasonably formed for when it comes to doing ladder tests on 4 different powders I'm minimizing the potential for bad/skewed data.

Originally Posted by Moa Hunter

Don't listen to those other fellas Willus, listen to the Moa.

Head spacing is the concern when fire-forming. If there is no formed shoulder to support the case it will be driven forward and then on ignition the case head will stretch back until it hits the bolt and bugger the case by thinning the brass or even split the case and separate the head. Probably stuff you have already been reading about. The very best way around this is to set your neck size die so that it does NOT fully size the neck but leaves a donut ring at the neck / shoulder junction. Adjust the die so that a case can be chambered but is firm on the bolt. The case is head spacing and held tightly in place between the neck ring and the case head. Load a normal standard load and go hunting

Cheers Moa,

yes Ive got the donut ring at the neck / shoulder junction. Ive adjusted all so that they can chamber and have also expanded the neck.