yes, logic tells it must be the dram for 27,27 grains

I read the maximum load for the .44 as 1 3/8 dram whats a little bit over 39 grains blackpowder and sounds rigth if you think about later cartridges like 44/40 or the original 45 long colt which was loaded also with 40 grains, iirc.

question was if britain and the united states still share the same dram around 1850 but if we look deeper america was still a colony in this for a long time.