Not sure exactly what you are asking but the case will blow out to the demensions of your chamber with the typical spring back. What is it you are exactly asking in regards to the .50 and .60 thousandths are you asking if a case can be blown out that much?

JLouis

I know what I want to say but sometimes it doesn't come through over the keyboard.

My example...
I have a tapered brass case that I want to fireform to fit a straight wall chamber.
The rim diameter, rim thickness, and the base diameter of the case are correct for the new chamber.
But, the tapered case needs to expand 50 to 60 thousandths to fit the new chamber.
And, lets say that the case is 2 inches long.
Can it be done?

Bp,
No case or chamber in particular.
Just curious.
I have the day off, it's cold and windy outside, and my mind is looking for something to do.
Thanks,
Dave

I've got some cases I fire form that are wasp like from below the bullet down towards the base before firing. They are mush more than .050" undersized, and easily form out to the chamber with no problem. The original case is a 9.3x74R so around a .367" neck, and I expand that out to .410" to make .40-85 brass. That leaves the wasp waste to the case.
They not only expand out well, but are pretty close to second firing in accuracy too! I use the same load to fire form them, that I use after they are formed.