A followup to my initial post:
Was at the range again today. Tried some additional groups with IMR4350 and 100 grain gamekings. I didn't expect I'd be able to duplicate .462" for the 50.8 grain load. That load came in at 1.149" today. I upped the load to Nosler's recommended maximum of 51.0 grains and got a 0.931" group. Of greater interest, when breaking in the barrel I loaded some Speer 100 grain spitzers with 50 grains of IMR4350. Following break-in I fired a 3-shot group that came in over 1.5". Didn't give that load much further thought, but I had a few cartridges left, so I shot 'em today. They grouped at 0.462".
I'm not too surprised by this. I realize wind, shooter error, or the rifle's capabilities will cause groups to vary, and you shouldn't put too much stock in one 3-shot group. Still, I choose which loads merit further consideration and testing based on that first group. I don't want to have to fire 3 3-shot groups of each load, although I recognize it's a more thorough approach.
Lest you think all I do is test loads, I also went through about 20 rounds trying the gun out from prone, sitting, and standing with shooting sticks. I like it. I also took my Rem 700 in .308 Win. to the range. The Ruger seems to fit a little better; and, based upon today's shooting, I shoot it better. Although I would bet that particular 700 (a VSF by the way) is a more precise rifle. Just goes to show that beyond a certain point, rifle accuracy fails to make much difference and shooter accuracy is what counts.