If you are fire forming 7mm TCU brass from 5.56, and are having headspace issues, we recommend the following:
Seat the bullet out long enough to firmly engage the rifling, put on a
firm Factory Crimp, and fire form the case using a moderate charge (do
not use light loads for fire forming).
Or, you are able to use an "oversized" decapper, in which we would recommend trying our 300 AAC Blackout Easy X Expander #SE3009:
https://leeprecision.com/ez-x-exp-300aac-blko.html
