Good morning gentlemen!!
If I may offer my experiences with mercury recoil reducers. The bulk of my experience is with rifles I have used them both on the Ruger #1 in 338 win mag, as well as my current tactical rifle in 7MM mag, and have shot both rifles extensively. As indicated, my friend Steeleco owns this one now, and he will be able to verify some of my comments from his own experiences.
While I have no direct experiences with their use in shotguns, I have spoken with at least one individual at my trap club that uses one on his BT-99.
When I had my Ruger #1, I was looking for recoil reduction alternatives. I had test fired some of my friends rifles equipped with muzzles breaks, and found that the combination of my sensitive ears, and increase blast were detrimental to accuracy. The next logical choice was to go to a mercury recoil reducer. I did some research, and spoke with my friend Rick at Alberta Tactical Rifle, and we settled on the product put out by C&H Research out of Lewis, KS USA as they seem to be the leaders in the field of this type of recoil reduction, are the high watermark by which all other systems are judge, and turn out a high quality product at a reasonable price. They have a web site (
http://www.mercuryrecoil.com/).
Rick installed this in the butt stock of my #1 and the changes were quite astounding, my 338 was now comfortable to shoot, the was much less muzzle flip, and the balance had improved.
After my 338 I was in search of my first full custom left handed rifle, and sold my #1 to fund the project. After much work, it turned out to be a Sako 691L in 7mm Mag, with a bi-pod. The Harris Bi-pod was to be a permanent fixture on the rifle but did weird things to the balance. So as I had an extra one kicking around we installed it. I like what it did to the balance, and now when fired, the rifle comes straight back, and time for follow up shots is reduced because of how it behaves.
The member at my trap club who uses it on his BT99 has the barrel clamp version, and he moved it up and down the barrel till he found his personal sweat spot. He found that extra weight up front gave him more control of the gun in his swing. He noted that while the recoil reduction is not as evident in a single round of trap, but the recoil reduction is very evident over an entire day of shooting.
Now, while I have sung the virtues of mercury recoil reducers, the down side it that it will add about a pound of extra weight, usually in the butt of the firearm. With shotguns, there is some flexibility as to where they can be positioned.
Further while it can be done, it is my understanding that it is difficult to instal such reducers in the but of a synthetic rifle stock as then need to be glassed in, and if done improperly can actually damage/break the stock.
These are some of my experiences. If you have any further questions please free to ask, and I will do my best to answer them.
Regards and all the best
R