Fire forming - seating depth ?

[tridiumk]

Hi all,

When Fire forming, what seating depth should i use? Should i jam the bullet into the lands to give the most pressure? Or can this slightly hinder the shoulder from moving forward?

 

[CK_32]

If your just looking to fire form nothing else just seat them at the standard 2.800 and load them out. No reason to full measure. If you run against the lands you run into maybe over seating a few and not being able to shoot the brass or have to measure out each OAL to make sure it will fit instead of just cranking them out with slightly varying OALs.

 

[HodgdonExtreme]

Depends on situation.

Fresh correctly-headstamped brass? Normal loads do just fine.

Wildcat that head spaces properly but has a lot of brass movement needed? Jamming can definitely help out to get a good sharp-shouldered form on the first shot.

Wildcat that DOESN'T headspace properly on the shoulder? You either create a false shoulder or you MUST jam bullets.

 

[tridiumk]

after 2 sets of firing without bumping the shoulder back on either set, it still isnt feeling tight to chamber... might take 3 or 4 firings..... !! annnnnoying.

 

[jkonzal]

One firing will form your brass to your chamber.

 

[HodgdonExtreme]

With moderate pressure loads, it takes several necksizings/firings before they chamber tight.

Feel free to do as you wish, but it is my opinion (and many others) that neck sizing only is inviting troubles like stuck rounds and galled bolt lugs.

If there is an accuracy advantage to neck-only sizing, I sure haven't seen it.

 

[Temp9]

What are you fireforming? Fireforming to fit your chamber is a different process than fireforming to create a wildcat. Also, some wildcats prefer certain techniques over others.

 

[gewehr]

Jam at least .020 into lands and use the minimum charge with the fastest burning powder for the parent case.

 

[tridiumk]

Fireforming my 338 Lap brass to my chamber...

I am finding 1 or even 2 isnt enough to make it tight, although, i think on the 2nd firing it might be finding the correct chamber/shoulder, because the variation in the cases from base to shoulder is only around 1 thou, so i'm guessing those are expanding to the shoulder, then cooling/shrinking enough to make the fit loose ?