Everything worked flawlessly, if not quite as smooth as I would have liked.
I woke up today with the notion that the strange grouping may be due to bedding problems with the stock. Except you can't "bed" this stock like a wood or plastic one where you open up the action area, slap in a bunch of epoxy, and mold it to the action. Instead, there are four setscrews in the bottom that have to be backed out enough to contact the trigger mechanism and apply the proper uniform pressure.
I think I can use some of that window caulk roll to check how things are compressing, and see if everything is uniform. After that, then see how much more the screws need adjusting to provide the proper pressure for closing the trigger guard.
Evening Win-Mag : nice target, especially the 10Xs. Very scientific analysis and expressed well in terms that even us caplock shooters can understand. Appreciate it. The 10Xs simply eluded me, I must have shot up my match quota in practice instead of during the scoring shoot.