I know about the Hornady gadget using special cases, but I usually use the simple "rod method" to find the zero touch length for a given bullet. But I thought I'd try a new method I've been reading about. You need to create a case expanded (or in my case split to hold a bullet) so the bullet slides easily into the neck. Next clean the inside of the case neck & apply a small amount of loktite & seat the bullet. Carefully load the dummy cartridge into the rifle & push it in & close the action. The bullet ogive touching the throat should push the bullet back into the neck. Set the rifle aside & let the loktite set. Later when you remove the dummy round you can use a comparator to measure the BTO (base-to-ogive). Worked like a charm for me!
BTW: Using the rod method my calculation was 1.448" BTO