I don't agree with this. I've had, oh, at least twenty, and maybe thirty Rem 700 rifles in assorted chamberings. And I don't recall any of them that couldn't shoot significantly better than 1.25" five-shot groups with good loads.
However, speaking of loads, I think you should try some Federal Gold Medal Match factory ammo in your rifle, as a benchmark. If it won't put three consecutive 5-shot groups into <1" groups, then I think your rifle is a clinker, and it's likely the barrel. However, the scope could be a culprit, esp. if you haven't dialed out the parallax and might be moving your head behind the ocular.
As to the stock, it's not fair or accurate to call it plastic, OP. It's quite likely an H-S Precision OEM stock, with their aluminum skeleton built in. 65" lbs of torque is quite a bit, but that setting works very well on my similarly-stocked Remingtons. At minimum, I would recommend 45" lbs.
The good news is that these rifles -- assuming it's otherwise in unaltered, original, excellent condition -- have very strong resale value, and somebody in the rude/crewd/lewd/skewed crowd over at Sniper's Hide might jump at the chance to buy the, um vaunted, 5R.
