The only ammo that I have shot 1 inch groups with out of my chrome lined 16" HB 1-9" Rock River is Black Hills 52gr Match Hollow Points.
I get close with my 50 gr Dogtown (Nosler) reloads.
Standard 55 grain fmj Federal or any other I am lucky to get 2 " groups with.
Any heavier bullets I seem to get from 2-3" groups.
I don't know if this is typical or not, but that is what I get. And oh yeah from a BENCH with sandbags, the whole nine yards.
Just leaning the rifle against anything gets me twice as much, offhand for me is really about the same as any other rifle at 100, custom or surplus, heck, my smoothbore SLUG gun for that matter but that probably has more to do with the fact I SUCK at "Awfulhand" than the rifle