Originally Posted by 80Maro
What I do is cut a slit in the neck of a empty case and insert a bullet so it's seated extra long. Thrn chamber the round and close the bolt. Carefully extract the case, making sure the bullet dosen't drag along the side of the chamber. Measure the case afterwards. Do this at least 10 times to get an average. You will start to see consistant numbers, disregard numbers that are way out to lunch, either the bullet was pulled out some when extracting it or what not. Works for me. I don't know if this is accurate enough for you, just throwing it out there. Do this for each bullet type you intend to shoot to find the distance to the lands for each type.
this works but two significant issues here the way it was explained.
1. this method does not measure where it touches. it measures the "jam" into the lands which is about .-040-.050 into the lands. does not it is a bad technique, you just need to remember where you are actually starting from, which is way into the lands.
2. You need a comparator to measure the ogive of the loaded bullet, and not the cartridge OAL. That can vary as much as .017 between bullets in the same box depending on that particular lot.
there are several technical articles on the reloading part of sinclair internationals website, giving very detailed instructions using several tools that they sell that work quite well.