Any time you add weight to the stock or in some cases the barrel of a shotgun the felt recoil is lowered. C&H Mercury systems used the weight and the movement of the mercury in the chamber to reduce the felt recoil respectively. They were offered in 4oz to 1 pound units and different dimensions to fit where the stock bolt is located. I have had several guns where the units were installed separately in the stock in a direct line from the barrel and they seemed to be much more effective but you have the added cost of installation. Be careful not to change the balance of the gun forward or rearward with any unit or you may find yourself swinging by or shooting behind targets... Trap shooters are always looking for that edge or 1 or 2 extra targets, Have fun finding yours.... Don
I had one in my BT 99 and it worked well. Not sure if the mercury or the weight. Mine was screwed into back of my Graco adjustable butt plate so moved with it when you adjusted LOP.
I use mercury recoil reducers and brass or lead weights (mostly in the stocks) and both help reduce recoil. While I do not believe there is much difference offered by the mercury reducers, I do prefer using them since it helps with dead space between my ears.
