I believe the % of mercury in dental amalgam is around 50%, by mass. Pretty high.

Even copper in the amalgam might be a possible concern, and with a combination of metals present, the influences of pressure etc, Liquid Metal Embrittlement might quickly become a complex issue in this potential application.

Another thing I've seen overlooked in gun work is hydrogen embrittlement from acid de-rusting, plating work etc where the hydrogen is not driven out by appropriate oven cycle. Pretty basic stuff but it requires some understanding of the metallurgy of the part etc. I've seen it overlooked often enough to suggest it here, might save someone some grief.