That's what I'm thinking Daryl. I Googled the term and learned that dram was an avoirdupus measurement and drachm was an apothecaries measurement and was equal to 60 grains.

Steve/Tinker, I'm right where you are in not having heard this before. Most of us have seen breech loading guns with the charge engraved in drams. But apparently before this 1878 English law, the drachm was used in conjunction with muzzle loading charges.

I'm not planning to run out right away and start running 160 grains through the old girl but it does tell me there should be no worries about working up a heavy hunting load, 130 grs to 160 grns, if this is all true. I'm still interested in what others think as it seems strange to not have read this somewhere before.