Yes, the mercury recoil reducers do help tame recoil. They have models that you can install in either the butt of the stock or in the forearm under the barrel or both.
For example... I had a customer bring me a Benelli SBE-II a few years ago because it would not cycle 2.75" 3-3/4 dram 1-1/4oz shells which the SBE-II should do quite easily. The Benelli shotguns require recoil to cycle the bolt. If it isn't there the bolt won't cycle. I went through everything inside that gun and couldn't find a dang thing wrong with it. Finally I took the butt stock off and found the mercury recoil reducer he had installed. Took it off and it cycled just fine.