Been reading reviews about the mercury recoil reducer, some say the mercury helps reduce recoil others claim it's just the weight. Wouldn't putting steel cold roll or lead in the bolt hole do the same thing without the chance of a leak.
The difference is that Mercury, while very dense is a liquid. As such it its center of gravity moves as a wave. This how it is supposed to work. I have my doubts , many trap and skeet shooters put it into the butt stocks of their shotguns. For the most part I think it was follow the leader syndrome, the problem is the the “leader” would have won regardless.