I would question the effect of spreading out the recoil that the mercury does upon regulation.

Some rifles seem impervious to messing with in regards to regulation. Add a scope, change recoil pads, add weight etc. They still shoot the same. Others are very senstive and even the slightest change will affect the accuracy.

By ading the mercury aren't you taking a chance that your rifle will shoot different (a) because of added weight and (b) by prolonging the recoil?

I don't know the answer and I have asked a couple of rifle builders and they don't seem to sure either. Anyone here actually used them in a Double? Doesn't Merkel or someone use them in their rifles?