That's what I noticed as well which explains the accuracy difference between calibers. The 308 is geared towards guys who want hunting rifle accuracy or want to blast away with cheap ammo. There is no need for a high end barrel for either purpose.
And without it actually being confirmed, (that I've been able to find anyways) I would hazard a guess and say that the stainless 6.5 CM barrel is made by Ballistic Advantage. Both the 22" and 24" seem to be the exact same contour and specs as the BA barrel. Not to mention that given Stags affiliation with BA and Aero it would make perfect sense to use the BA barrel.
If I'm correct in my assumption that the 6.5's are using a BA barrel I think people buying one of these guns are going to be rather impressed. BA makes an extremely accurate barrel for the money.
Some confirmation from Stag or AE on who makes these barrels would be appreciated.
Given Canada Day, and the upcoming 4th of July celebrations, I don't think we'll get 100% answers on anything from either side of the border... which sucks since all these "Canada day sales" will have then expired. Such bs.