I use a fired case, resize only about an 1/8 of the neck. insert a bullet by hand, color it with a magic marker, chamber the dummy round, carefully remove and measure. Repeat several times to verify COAL. The key thing is having a bullet that is held by a minimum ammount of neck tension.
Then I fully resize a case, seat a bullet to the COAL, chamber it, look for the marks from the lands and then start seating the bullet deeper in .005 increments and look to see where full contact is, partial contact and no contact. This will absolutely show where the lands are for a given bullet in your rifle.
There are tools that make the job easier and faster but results shouldn't be any different.
To avoid pressure issues, I don't seat bullets into the lands.
fish head
