Interesting case. Some very good points have been brought up.
The Bead Blasting should have made no effect on the rifles accuracy as far as the rifles fit to the bedding. I say this because every rifle I build for customers, around 80 to 100 yearly, every one is bedded prior to bead blast finished the metal surfaces. Simply put, it will not make any difference. If the barreled receiver is tighter going into the bedding, its for another reason, not the bead blasting because the blasting will actually remove a minute amount of steel. The blast media actually cuts the surface of the steel which is why it changes appearance. It in no way increases in size unless your smith is using gravel for blast media.
So what will cause the accuracy problem, well, reading over your post I see several issues that MAY cause problems. I will go over each. Something happened and changed from when you broke in your barrel to when you get the rifle back. Lets look over what has changed:
3. Wyatts magazine box. If its the internal mag box that used a Rem 700 BDL floorplate, you have to make **** sure that the magazine box is free floating between the receiver and the floorplate. You should be able to open the hinged floorplate and reach inside with a couple fingers and be able to move the internal mag box some both on the front and rear of the mag box. If it will not move easily, its binding between the receiver and floorplate and you are not getting a solid hold on the receiver screws holding the receiver down into the bedding. This can cause SERIOUS accuracy problems. Also, make sure that the feed lips on the mag box are not contacting the bolt, if they are, they need to be shortened.
+1
The bedding should not have changed from blasting but if the mag box is tight and cannot be
moved with little effort after the action screws are made up it will flex the action and will generally screw up the consistency of the rifle.
All mag boxes must be non binding or they will hurt accuracy.
J E CUSTOM
