I'm working on building a 7mm wildcat right now. I know what bullets I'm wanting to use and what not but I dont know how to make sure I have the freebore correct for the bullets I'm going to use. Can someone tell me how to make sure I have the correct freebore for the bullets I plan on using before I send out the dimensions for a custom reamer.
Given your going to have the reamer made all you need to decide is how much room you want to leave for throat erosion to chase he lands and what length will work in the magazine and how much jump you want the bullet to have......sounds complicated, it's really easy.
1. what is the max magazine length (2.890")
2. Known bullet likes to jump (+.020" or whatever)
3. You want .050" of erosion to chase lands (-.050")
4. Magazine clearance (-.010")
OAL= 2.890-.050-.010+.020
OAL= 2.850"
Load the dummy round at 2.850" and have the reamer ground...... I load three dummy rounds to send in to the remaer manufacturer.
When you load live ammo your OAL will be 2.830" and you can chase the lands to 2.880" and still have .010" clearance in the magazine.