Instead of following through with my last post (using molten lead to hold the recoil buffer in place), which was a silly idea anyway, I ended up just pouring epoxy around it.
Anyway, moving along.... Went to the range today to try this thing out. My Marlin GG is a blast to shoot, but it became "not-fun" after a short while at the bench. Call me a recoil wimp... I'm OK with that. Well, I don't know if it was just the added weight (got the 16 oz version) or if the mercury was a benefit, but it definitely helps with the recoil. A VERY noticable difference. I highly recommend them.
Robert