I built a .260 Remington a few years back and had it chambered in a "Match". That gave me a little more freebore than SAAMI spec. It allowed me to seat the 143 ELD-X way out to take advantage of the case capacity. Being that you're referencing the 147 ELD-M I'd say that you probably want more freebore than less. I bought a Criterion prefit barrel, but I can't remeber how much more freebore they said it had.