With the 300 savage brass, after every 2 firings or so, I had to trim quite a bit due to the case stretch. With 308 brass, being heavier and thicker than the savage brass, I have fired as much as 5 times before needing to trim, and then there was very little to trim.
I believe the 307 brass, for strength, is in the same neighborhood as the 308.
:grin: