dem4570,
I never put loctite on the ring screws, just a drop of loctiteon the base screws after you've cleaned the threads out on the receiver and the threads of the screws.
You said you dbl. check the ring screws, but didn't mention the screws on the base. What type ring/base set up do you have? Are you consistant with your seating pressure? Is this a new or used scope?
If you know everything is good to go, all you need to do is find the correct load.
I'm very fond of the Barnes bullets and I've had good results with Power Belts and the Precision Dead Centers.
I haven't shot Pyrodex R/S for awhile, but when I did I always made sure that I mixed the powder up. The fine stuff makes it way to the bottom of the jar and it will shoot differently than the larger granules on top. I'd be interested if anyone else has experienced this with Pyrodex too.