Question on cases, new and once fired

[jerrya]

I am working up a load for new to me winchester mod.70 chambered in 270win. I am using new starline cases. I have found a very promising recipe with the new cases. I took the once fired cases and measured h20 capacity after sizing to compare to volume of the same cases when new I had previously measured volume. Resized cases show 1/2 grain more volume than the new cases.
I have not reloaded the once fired cases and tried them yet but was curious if others had to adjust powder charge to achieve the same results as the resized cases now have about 1/2 grain more capacity?

 

[bigedp51]

Quickload tells you to measure the case capacity of a "FIRED" case from your chamber. And a resized case should have less capacity because you reduced its diameter.

 

[todbartell]

The volume of a virgin case will increase in a millisecond. I have found I usually have to reduce a load around 1% going from virgin to fire formed and resized minimally (.002" shoulder bump) brass, to maintain the same velocity as the virgin case load.

 

[Buckmastr]

The pressure required to expand the brass is nothing compared to the peak pressure. I load them the same.

 

[Leatherstocking]

I’ve had good results using the same load in once fired cases as new. But I’m a 1moa hunter.

 

[Hitzy]

Most virgin brass won't even get sized in a FL die other then then neck, generally fairly undersized.

 

[jerrya]

Maybe my method or scale is wrong but this is what I got over the same 5 cases
new- av. capacity h2o 67.8 grns
once fired, not cleaned or sized - 68.44 grns
once fired resized wit .002 shoulder bump - 68.3grns
And the new cases (starline)to the shoulder were 2.043" they were a bit stiff chambering
once fired(not sized) to the shoulder is 2.0395"
I bumped the shoulder back to 2.0370" These chamber much better

 

[JEC]

The only correct answer will be answered by your rifle. Reload, fire and let us know what it says.