re: PSA H&R 35 Whelen scope rail

REB BEER,
Sorry to hear of your bad luck. Whenever I buy a gun that already has a scope mount attached, I always take the mount off and reattach it. That way, if I have any accuracy problems w/ the gun, I'll know it's not related to the scope mount. Here's the procedure I've developed after many years of shooting:

1.Remount the base, using BLUE Loc-Tite (NOT red). I always use the $10 Weaver bases, even on my prairie dog handguns; I'm not familiar w/ the PSA mount, but hopefully if's of decent quality. Before installing the scope base w/ Loc-Tite, individually check the length of each screw. Put the base in place, then screw in a screw into the intended hole. If the screw is too long, cut off the excess w/ a Dremel tool or get a new screw. If the screw is in all the way and the base is not tight, the screw is too short. It should have a minimum of 3 threads for it to have adequate strength. If it's too short, it will need to be replaced. Remove the screw and repeat this step w/ each screw in a different hole. Each screw should be tight enough to attach the mount very tightly.
2. Remount the rings. I don't use Loc-Tite on the rings. Be sure the screws attaching the upper/lower rings are equally tightened. If the rings have not been lapped, do so. If you don't have the equipment to lap them or don't feel comfortable doing it, change the rings to Burris Signature Z-Rings (the ones w/ plastic inserts).
3. Use a torque wrench (and follows it's recs) to adjust the mount, rings and action screws. I like the Wheeler torque wrench.

Good luck! Let us know how it turns out.