I haven't tried their 7.62 Nato ammunition but I did pick up a couple of sealed cans of their 5.56 Nato a couple of years ago.
At first I thought it was crap. I shot it through three different known to be accurate rigs and my groups were similar to yours.
Then, shortly after reading a discussion between Ganderite and a couple of other good CGNers, which was about why a great batch of surplus ammo wouldn't shoot well, after an over winter storage.
What they agreed was the cause of the recalcitrant ammo was CASE NECK TO BULLET WELD.
I had never heard of it before. I had what I thought were bad batches of surplus ammunition before, especially 303Brit and 8x57.
One thing I had noticed was when I bought large quantities of surplus ammo, say by the pallet or two, that had some sort of sealant, everything from black, tar like to red or green nail polish, shot pretty well. So, if I possibly could, I bought it in quantity. Most for my own use, but also for resale several years later, at considerable profit.
What did I have to lose by breaking the case/neck weld?? Nothing that I could think of.
So, I took a hundred rounds and ran them through my reloading press. I only pushed them back .005 in. and it made a huge difference. The groups weren't stellar but almost acceptable for their intended use.
I ended up pulling all of the bullets and blending all of the powder that came from those rounds. Then, of course, I reassembled everything back to .010 in over its original length.
It was as if the sun shone on those rounds, the rifles they were used in shot them around 3/4moa at 100 and opened up about half an inch at 300.
I'm not saying that this will work for your ammo, but what do you have to lose? Give it a try.
Before reloading the ammo, weigh those bullets, if the weights vary to much, which I doubt they will, then sort them by weight before reloading and keep the different weights separate. Each of those weight groups will likely group very well.