Well, I took some advice from the board, and here's what happened:
Background- shortly after I bought the rifle, I had a muzzle brake
installed. I decided to have it removed, the action glass-bedded, and the crown re-cut.
Turns out the "gunsmith" who installed the muzzle brake in the first place rolled the crown! No wonder the accuracy was poor! I took it to a different 'smith this time. The rifle was taken to the range on Saturday with its new bedding job and recessed target crown, and the results were surprising.
I turned in all sub-MOA groups with factory ammo, including one .65" group with Federal Premium HE 250 GR partitions. What a difference!
Thanks for the input and advice.