Iirc, I've read Bill Calfee saying threading the muzzle can blossom the bore by .0001"
That is one ten thousandth of an inch!
Blossom!
Most people can't even measure that small.
Haven't read all the posts, but I had a barrel that would not do what I thought it should and had the barrel crown redone and helped quit a bit.
Who diagnosed your friends problem and what was the outcome? You just threw out two very reputable names. I have a Gradous built 6.5 on a Bartlein barrel and it is one of the finest shooting rifle I've ever owned. I know if I could only get 3/4 MOA out of it after trying everything my first call would be to Robert and he would gladly trouble shoot it if need be. As in this thread a lot of the good suggestions are among a few of the many other things it could be.
That's why my friend bought the rifle/Gradous and Bartlein. My friend is the 2nd owner so we both think the rifle was sold because it wasn't a great shooter?? Supposedly it only had 250 rounds through it when he got it. Everything else about the rifle is top notch as far as build quality.
Since it's not my rifle I can only make suggestions, I'll tell my friend to call Gradous.
thank you for letting us know how your doing,,,,give yourself a little credit,,,that is a good group,,,that is as good as target rifles do most of the time,,,out in real conditions with a hunting gun ,,,that is as good as it gets,,,OBTW what load did it like ???....Roger