load development with new brass???

[djtjr]

hey guys, assuming a case does not have to be fire formed to form a new case dimension ie a 6 br to a dasher, can you reliably do load development with fully prepped but unfired brass? in other words do you do load development on the first firing of a new batch of brass or wait till it has conformed to the chamber them bump back .001-2". I would think that cases where there is a significant volume differential like my example above it would be difficult to develop a load with, though you may still shoot accurately, but what are your findings say using 6 br brass in a 6 br? do you find that everything remains the same on the second firing with the load that shot best in the first firing or does it change up the second time around?
thanks
Don

 

[1000yardstare]

In my 6AI, I see no difference in accuracy when fireforming the first load in a new case. But there is a velocity drop compared to the second load in a fireformed case.

So I only fireform during short and mid-range F Class practise, not competition. Don`t believe in having special fireforming sessions that have no relation to F Class practise. This just sends bullets down the barrel with no development of wind reading skills and takes that many rounds off the life of your barrel.

 

[alf]

In hunting/varmint type chambers, I start with load development right from the get go with new detailed brass.