"For the “Any sights, Any Rifle” and “Iron Sights, Any Rifle” stages of the Long-Range Championship, John used three different .243 Win rifles. He shoots the same load in all his .243s: Berger 105gr VLD bullets (moly-coated) with N160 powder and PMC (Russian) primers. The bullets are seated very long, with about .001″ neck tension, so the bullets “soft-seat” themselves into the rifling as he closes the bolt. This way he can use the same ammo in different guns and the bullets always find the same seating depth relative to the rifling."
How come no one ever mentions doing this on the forum?
I, for one, am reluctant to expose myself to all the, "Yea, but I...'s".
Neck tension is a tweak that many shooters don't bother with it. Accuracy shooters do. Personally, I use .001-.0015 tension. Jump .002 Hybrids, jam flat bottoms for short range 14 twist. But now, I am going to try (what you posted) some just deeper than touching because I went from jam (105 hybrid) .002, to jam .001, to jump .0020. Extraordinary results. Depends upon your firearm and its components. Maybe his practice can benefit me as well.
I am still learning and there is a wealth of information here if you know where to look, what to take as gospel, and HOW to ask specific questions.
Regarding be able to shoot in different guns? Smart. Good to know.