BigMac53,
This is how I determine seating depth. I read it in a Layne Simpson article and he called it the "HLEP"(Head to Land Engagement Point) method.
Here goes:
Into one of your fired and unsized cases, insert one of your flattest based bullets, backwards. Place this cartridge into the chamber and gently close the action. You want the bullet to slip, but stay in place when you pull it out. This will measure the distance from the case base to the beginning of the rifling. Do this several times to verify the distance.
Record this measurement!
Now place one of the bullets you are loading, into the muzzle(point in first) and spin lightly so the rifling will leave a ring on the bullets ogive.
When you seat this bullet in the normal manner, you can measure from the ring to the base of the cartridge and adjust as far off the rifling as you want.
Use this bullet in your first loaded cartridge and set the seating depth with it.
I hope this is clear! :shock:
Buffalogun