What scope rings being used? I've found that many of the older Weaver rings that have the steel top straps using slotted screws had a tendacy to loosen up easily compared with the newer aluminum rings that have gone to hex drive screws. These newer hex screws also have larger heads and maybe why they hold better under recoils. At least they do with all my scope mounted guns. I also line the scope saddle and top ring with a strip of electrical tape to help hold the scope better from slippage when tightening down the top straps. Been doing this for over 40+ years with no problems.
If you want to keep the scope ring system you're now using, have you tried using lock washers with the screws? Might help in this instance. Washers won't work if your top strap screws have a bevel on screw like many of the older Weaver screws had. If this is the case, you might want to see about some new screws with flat heads and then install the lock washers.
If nothing else, I've used clear nail polish on the scope ring screws to help keep a bite, while being easily removed if needed. Just spray some brake clean on the screws and the scope saddle base to clean out any oils to make sure the screws lock down when the polish dries. Never use any (Blue) Loctite on these screws as they don't take high torque to snap off or strip the slotted screw(s) when trying to remove. Usually only 10-12 (inch) pounds is all that's needed. NOW, definitely use blue loctite on the base rail scope mount screws as they're larger, to hold things solidly and those screws are generally torqued 20-30 (inch) pounds and depending on if the gun's drilled receiver is aluminum or steel.
