I agree with Searcher. You can get down to near .5 MOA with a lot of effort, but don’t count on it, and very unlikely “out of the box”.
There was a good article on the precision Rifle Blog about accuracy from some high end 6,5 CM AR10s and a bolt gun in 6.5CM:
http://precisionrifleblog.com/2016/07/22/6-5-creedmoor-ar-showdown/
My experience is more limited than Searcher. I got good accuracy from one rifle with a lot of effort, but not very good results with another rifle. These are both weapons I assembled rather than purchased as a complete rifle - building them is way too much fun to let someone else do it.
I have a “medium-high-end” AR10 in 6.5CM. This rifle has a 22” Rainier Ultra Match barrel, JP high pressure bolt, cheap DPMS bolt carrier, Geissele SSA-E trigger, Magpul PRS Stock, and a Leupold VX-6 4-24x52 (34 mm) scope. The most consistent factory ammo I found could barely beat 20 fps SD, so I got some custom loads to test. The custom load shot well around 0.6-1.0 true MOA (corrected for shot count) during load development with Berger 140 Target Hybrid bullets in Hornady brass. I didn’t buy enough ammo so I don’t have the load recipe, but here are the true MOAs from 5 consecutive 5 shot groups at 201.2 yds with different powder loads and COAL 2.80”, shot off the bench with a Harris bipod with a rear bag:
0.887 starting load
0.998
0.644
0.646
0.582 max load
Then I started measuring MVs and these were more inconsistent than the factory ammo, so I stopped buying the load. I’m gonna start reloading soon, hoping to have reasonably good precision and more consistent MVs. As of today, I was able to buy the 140 Berger Target Hybrid bullets - some of you will know these have been hard to find for a while. If I can get a load I’m happy with, I may use this in some PRS matches, but so far it’s not as good as my bolt gun with factory ammo. I need all the help I can get.
I also have a medium-end AR10 in .308Win that I’ve only been able to shoot less than 1MOA
only twice after shooting many groups. I found several factory loads with very consistent velocities, but I also shot about 25-30 5-shot groups with these factory loads and almost all of them were somewhere between 1.05 and 1.25 MOA. I would like to shoot this rifle at 1 MOA & smaller targets at 400-800 yds, but the hit probabilities are pretty low with that sort of precision. This rifle has an 18” Rainier Ultra Match barrel, Geissele SSA-E trigger, Magpul UBR gen 1 Stock, Leupold VX6 3-18x50 (30 mm) Scope, and I don’t remember what bolt or bolt carrier — it’s been a few years since I shot this rifle. I had some issues with the bolt and carrier and it took significant effort just to get the rifle running well, and I never managed to get it to shoot well, at least not yet.