.002-003” over groove diameter ( sized, lubed, gas checked- if g.c. design). I cast for .308” ( 30-30, 308 Win, 30-06), .358 mag/ 38 Special, 44 mag, 45-70. Might be different for .224-.257 bore ( may need .002”).
You need to slug your bore first, to find YOUR starting point for groove diameter.
