When you say "glass" bedding I assume you mean epoxy. You say your barrel is free floating to within 4" of the action. If that mean the first four inches of the barrel just ahead of the action, that might be part of your problem. I think most people bed the action and perhaps and inch or at most two of the barrel. Four inches seems like a lot, at least to me. My Savages, for example, have the barrel nut bedded, but nothing forward of that. A few minutes work with a Dremel tool might be a good idea.
As others have pointed out, you gotta' do charge weight experiments and seating depth testing from scratch.
I hesitate to say this because the theory of a barrel getting much better after a couple hundred rounds is not something I have much faith in. Perhaps a little bit, but not a lot. However, a new barrel on one of my .223 rifles seems to be exhibiting such behavior. Initial tests produced some promising 5 shot groups with MOA in the 3's along with groups worse then 1 MOA with charge weights only a half a grain heavier or lighter. I was worried. Now; however, after 250 rounds down the bore, the gun is behaving better with quite a few 5 shot groups at 100 yards in the 2's and charges a bit heavier or lighter not a whole lot worse. So in spite of my skepticism, perhaps your barrel will improve with time.
Good luck.
