Case Stretch

[Kurt]

Check the rim thickness on your new brass to make sure they did not make a change. A change in head space can be a problem.

Also my .40-70 cases tend to stretch more back when I used the oil/water wiping solution with freshly annealed brass caused stretching and the problem ended when I quit using it.

A unsized case to close to to the chamber end transition and if full length sizing it gets longer and when the bullet bumps up tightening past the transition the longer brass will stretch.

Best tool for inside neck trimming