We have them in several guns. Both mine and my sons single barrel traps. Also in my son's beretta silver pigeon II sporting gun. They work better than just dead wt. (I have dead wt in my Bronwing Citori Sporting) They do change the balance of the gun. This is important. I wanted that in the guns I installed them in sometimes as much as the recoil reduction.
I firmly believe that recoil is an enemy to all who shoot significantly. (target shooters). Don't be afraid to try low velocity loads. I have shot a lot of Winchester low recoils 15/16 of 8's at 980 fps. They break targets just as well as the fast stuff.
Jerry
