You must 'fit' all barrel swaps for correct headspace. My most accurate hunting rifle is a M600 with a M700 barrel. Easy swap. PacNor used to sell take-offs for $75 and guarantee results even after fitting. They'd give you your money back if not satisfied. That's where I got mine. In club 'hunting rifle bench rest meets' firing 20 rounds on 4 targets, this rifle averages .8" and wins consistently.
