From my understanding, it's not so much the barrel as it is the block/tube intereface. There's been mention of improved chambers on the barrels that have been manufactured over the past 18 months or so.
I had an accuracy issue with my early M (08XX) and the gas block/tube update did cut my groups in half. I've not shot much of the new barrels so can't speak with much authority on those.
They were offering the block/tube update for free. I went from 2.5MOA to MOA...ish after the update. I've got a thread in the "M" section that details my experience. It's up to you to figure out if it's worth the update for a whole new barrel, or just try the update.
Not sure how they're doing it North of the border.