Fire formed cases?

[rebs]

How do you guys' size fire formed cases? If you fl size them, do you lose the benefit of fire forming?

 

[jepp2]

How do you guys' size fire formed cases? If you fl size them, do you lose the benefit of fire forming?

I size them so the case head to datum is 0.001" shorter than my rifle headspace. Generally after a single firing, the case is still shorter than that, but the sizing die squeezes the length longer before it bumps the shoulder shorter. New brass is normally much shorter than your headspace. You don't lose the benefit, if you measure and set your die correctly. I also set my neck tension at what I want. Some of the new Lapua brass I've fired had very high neck tension. On those I used an expanding mandrel before I loaded them.

 

[Dave Zander]

I full length resize. I was told to remove my firing pin on my bolt guns, this way there is no tension /resistance on the bolt when its in the receiver, it will drop freely. Then I size my fired case and put in in the chamber and close the bolt. I adjust the sizing die so that the bolt almost falls down within about a 1/4" of being fully closed. You can take a datum measurement on that case if you like so you can reset your die if necessary.