I've always fireformed my brass, but recently came across a method that worked to achieve the same results without spending components even once! There must be a reason I haven't run across this much, yet see countless amounts of threads about fireforming.
Can a more experienced hand loader tell me why folks are fireforming instead of using this process?
First we need to find headspace, one way this is traditionally done is through fireforming until you find a point the bolt meets resistance closing, then backing off 0.002, setting your die to that measurement.
Here is scenario. Using Forster full length sizer dies, pin removed with Hornady one shot case lube on a RCBS chucker:
Maximum headspace: 1.5695
Ideal Headspace :1.5675
New brass headspace on comparator : 1.5625
When fireforming the first go brought it up to 1.5645 with a pressure around 53000 PSI.. still requiring a second or third to get it where it needs to be unless our full sizing process also "stretches" the case if the die is adjusted, (it does)! ... This got me to testing.
Same new brass out of the box, non fireformed right into the full length sizing die adjusted to 1.5675, and what do ya know.. The brass "grows" to exact measure without a single firing or component used to form the case.
In hindsight, you could also find the initial maximum headspace by running your die long and simply backing it off till you find a measure that chambers and not have fired a single round.
So in the end the question is, is there a reason folks are spending components and putting brass through 2 or 3 firings when it can be eliminated by the sizing process?
Can a more experienced hand loader tell me why folks are fireforming instead of using this process?
First we need to find headspace, one way this is traditionally done is through fireforming until you find a point the bolt meets resistance closing, then backing off 0.002, setting your die to that measurement.
Here is scenario. Using Forster full length sizer dies, pin removed with Hornady one shot case lube on a RCBS chucker:
Maximum headspace: 1.5695
Ideal Headspace :1.5675
New brass headspace on comparator : 1.5625
When fireforming the first go brought it up to 1.5645 with a pressure around 53000 PSI.. still requiring a second or third to get it where it needs to be unless our full sizing process also "stretches" the case if the die is adjusted, (it does)! ... This got me to testing.
Same new brass out of the box, non fireformed right into the full length sizing die adjusted to 1.5675, and what do ya know.. The brass "grows" to exact measure without a single firing or component used to form the case.
In hindsight, you could also find the initial maximum headspace by running your die long and simply backing it off till you find a measure that chambers and not have fired a single round.
So in the end the question is, is there a reason folks are spending components and putting brass through 2 or 3 firings when it can be eliminated by the sizing process?
