Replace barrel and form fitted casings

[DesertDug]

I have casings that we're form fitted prior to changing out my barrel, are they still good to neck size only or do I need to full size them now due to new barrel?

[sharpshooter]

Full length size

[DesertDug]

Ok thanks, is this because there is different pressure?

[yobuck]

By the time you tried each one in the gun to be sure it fit the new chamber, which could have slightly different dimensions, you might just as well run them thru a full length die instead.
It's just one ingredient in the soup anyway, and we could have a long debate on how much it actually means.

[243LPR]

And you'll only have to do it once.

[Stumpkiller]

Ok thanks, is this because there is different pressure?

More than likely different headspace.