Scope moved while shooting.

[CAMPMEAT]

Torque them to specs with blue loctite...

[Cab]

Or these...
http://www.talleymanufacturing.com/

Haha those are good ones too Jerry. Elkoholic was with me in Montana one year when I had the same problem you’re having. I had a pretty good set of rings by Burris and had loctite but they still worked loose! I am not a fan of 2 pics bases anymore, IMO one less thing to have fail with a one piece   

Is this a magnum round by chance?

Just shooting normal 165g Federal Fusion. Thanks for the insight!

[yakimanoob]

+1 for quality rings and loctite blue. 

Do not skip the loctite, and make sure the setup is clean when you're installing.