If you do figure out how to loosen them, you'll never get them tight again. I know because I've done full repairs on the RWS scope rails where someone did manage to get it loose--ugh.
If you can drop about $40, B-Square makes a great rail-attached device that is designed only for droop, no windage, and holds very well. It clamps on a dovetail/11mm riser, and provides its own adjustable 11mm riser directly above it. It's easily re-adjustable if you move it from gun to gun, but it stays put once tightened. I think everyone should have one in their airgun parts bin, just in case their next airgun comes drooped to the max. Have a look:
For even less money than that, take a few shots with your scope centered at 10 yards, and send the resulting target to Tim at Mac1 with your own scope rings. He'll machine the rings to cancel out the droop up to 4" or so--(you'll have to check his site about the maximum droop amount; he can even do a little windage adjustment). In any case, your newly droop compensated rings will stay put forever.
The Airgun Tune-Meister
"We can rebuild the squirrel. Make him stronger, faster...We have the technology"---S.M.