Dasher case forming question.

[benjamin199]

I am going to be fire forming 6 dasher brass using the false shoulder method. I have my cases prepped, my necks expanded on a 25 cal K & M mandrel, then brought back down using a Forster full length sizing die to the point where I just feel a slight resistance when closing my bolt with the firing pin removed. Is it a good idea to anneal my cases before fire forming, or should I just seat the primers load them and form them without annealing the brass? I do have a Ken Light annealer so it isn't much of a bother to anneal the brass.
Thanks for your input,
Ben

 

[techshooter]

Ben:

If they are brand new Lapua cases, then there is no need to anneal, as Lapua brass has a perfectly heat treated neck right out of the box. If, however, your cases have undergone multiple firings, then annealing of the neck and shoulder would be a very good idea. The work hardened necks and shoulders of older brass can split during fireforming. Also, annealing relieves stresses that may be in the work hardened brass, so annealing after you have expanded and prepped for fireforming is not going to give you the best results as the necks may not have consistent dimensions post anneal. On a general note, it is best to use new brass when fireforming, as older brass has taken on the characteristics of the last chamber in which it was fired, and you may not get the best brass consistency (especially concentricity) with them, at least as compared to new. I get about 1% split necks even with new Lapua brass.

Hope that this helps!

Cheers,

Chris

 

[benjamin199]

Chris, thank you for the reply. I am using new lapua brass, so I will load them up.
Best regards,
Ben