Just for clarity I use a nylon coated cleaning rod, not a steel rod like Ian. I use a Parker Hale jag (rounded tip) on the rod to contact the bolt face and then the bullet nose. Make sure the firing pin isn\’t protruding from the bolt face while making the first measurement. I use Possum Hollow cleaning rod stops rather than brass stops. A micrometer adjustable bullet seater takes the guess work out of setting the proper bullet depth for the dummy round.